update, 13 April 2021 Big thank you to Rachael Adrian (48789962) for her photo. She wrote .. No headstone, but I have checked the location according to the Tararua District Council. The grave to George's left is site 'Block 13, Plot 82'

George Walton was born c1857 possibly in Leicestershire , to John Atkinson Walton (1826-1900) & Jane Mary (1831-1891) . NZ records have he was 38 (his badly decomposed body was found a month later so aging would have been difficult). A kind reader has sighted his memorial on the headstone of his parents in Lockington, Leicester and it states he was 33. He will upload the photo when he can. George's brother William (1859-1890), also on the headstone, died 3 months before him in Nottingham. You can see the stories at their links below.
. NOTE . I decided to link him to his fiance Mary Rose Rees (1859-1930). They did not marry of course, but were engaged and due to marry shortly after his death date in 1890. This is so you can read her family's profiles and the people he knew so well, (worked and played cricket with). Mary Rose's father, William Gilbert Rees (1827-1898) is credited with being the founder of Queenstown. In 1860, he, along with Nicholas von Tunzelmann (1828-1900), was the first European to explore the Lake Wakatipu Basin and established a homestead at what became the town of Queenstown. Mary Rose married James Wilfred Marsden on 21 Dec 1900 in the Napier Cathedral.

George Walton was last seen alive on the Manawatu Gorge Bridge on Friday afternoon 8 Aug 1890. When his body was found a month later his watch had stopped at 4 p.m. Interment date was 4 Sep 1890.

Woodville Examiner, 13 Aug 1890
A SURVEYOR MISSING On Monday evening the police of Palmerston communicated with Constable Treanor as to Mr Walton, a surveyor of Palmerston, being missing. It appeared that Walton came to Woodville on Friday and left again for Palmerston early in the afternoon and had not turned up. His friends became anxious and made enquiries about him. Yesterday Constable Treanor proceeded to the Gorge and ascertained that about 2.30p.m. on Friday Mr McGonagle met Mr Walton on the upper Gorge bridge, the latter on his way to Palmerston. Mr McGonagle spoke to him. Nothing more appears to have been seen of him. About 3 p.m. Mr Thompson found the horse (with saddle and bridle on) which had been ridden by Mr Walton. The near stirrup was thrown over the saddle as if the rider had been thrown off. The horse was found about a mile on the other side of the Gorge bridge. No notice appeared to have been taken of the matter at the time but it is now evident that Walton must have been thrown from his horse down the cliffs between the bridge and a point a mile in the Gorge. The surfaceman who was working a mile along the Gorge road saw neither horse nor rider.
Constable Treanor searched the steep cliffs as well as he could from the road but could see nothing of Walton. The growth above the river is a dense scrub and Constable Treanor went through it as far as possible. Still it is extremely difficult to make a proper search of the place from the road and Constable Treanor went there again to-day with M. G. L. Rabone to search the bank with aid of a marine glass from the railway side and if possible to procure a canoe and traverse the river in the vicinity. Of course Walton may have been thrown into the water and drowned. He was a stout, heavy man and if thrown form a horse would probably sustain a serious injury. He may have been seized with a fit or heart affection while riding or as a result of the shock of being thrown from his horse. Constable Treanor will endeavor to obtain assistance so as to make a thorough a search as possible.

Woodville Examiner, 18 Aug 1890
TRACES OF WALTON On Saturday Constable Treanor proceeded to the Gorge and made another search for Walton. Detective Grace arrived by the morning train from Napier and proceeded straightaway to the Gorge joining constable Treanor in the search. So far as we could learn, however, they could discover nothing further
A LETTER On Saturday morning Mr Woods, who works at the Gorge Bridge, brought Mr McGonagle a letter which he had picked up on the bridge between 4 and 5 p.m. on Saturday week. The letter was addressed to G. Walton from W. Earl Lindsay of Wellington and bore date 9/8/90. It was found on the wheel-guard rail of the bridge, but Mr Woods thought no more of it till Friday night last, when reading the account in the 'Examiner' of the mystery, he recollected Walton's name as being associated with the letter and looked it up. On Saturday the letter was handed to Constable Treanor.
A BANK SLIP On Saturday morning a lad at Ashhurst found a bank deposit receipt slip for a sum of £13 odd lodged by Walton to his account with the Bank of New South Wales, Wellington, in May last. This slip was handed to Constable Brown of Ashhurst.
THE SEARCH PARTY The time fixed for the departure of the search party from Woodville was 9.30 a.m. Mr Peters generously placed two coaches at the public disposal for the conveyance to the Gorge of the search party. These were crowded inside and out. Several were unable to find room and either remained or came on afterwards. A good many rode down. The departure of the search party presented a busy scene between the Club and Masonic Hotels and a good many townspeople assembled to witness the departure. It was most creditable to the people of the town and district to see such a large and willing assemblage of a mission of humanity. Assembled at the Gorge Bridge the men were addressed by Constable Treanor who suggested the manner of search so that the river bed, river banks and bush above the road should be thoroughly searched. Mr Marshall was in charge of the search party above the road and a more thorough search of the locality could not have been surpassed. Detective Grace took the right and Constable Treanor the left bank. Every nook and corner which could be got at was thoroughly searched
PARCEL OF PHOTOGRAPHS On the left bank, a short distance below the Gorge Bridge, Mr G. L. Rabone found a parcel which had been in possession of Walton containing photographs - one a group which included his friend Mr Lindsay and the other a vignette of Miss Rees, to whom Walton was engaged to be married. Mr Lindsay and Miss Rees arrived on Saturday to enquire into the mysterious departure of the deceased and both were in the Gorge yesterday while the search was being prosecuted. Enclosed with the photographs, where were wrapped in a piece of newspaper, was a letter from Mr Marchant, Chief-Surveyor, which was evidently a testimonial to Walton's work while engaged by the Survey Department.
ANOTHER LETTER A little further down the river on the left bank, Detective Grace found another letter from Mr Lindsay to deceased. This letter was tightly fixed in the root of a large tree and at a height of two feet above the present water mark. This showed there must have been two feet more water in the river at the time it was lodged there by the water. The photographs had been found at a point a similar height above present water-marks, so that these things would seem to have been carried along the river at about the same time.
UNTRUE REPORTS It was reported on Sunday that a satchel which Walton had over his shoulder and which is supposed to contain valuable papers, was found in the river below Ashhurst, but this report proved to be untrue.
SEARCHING THE RIVER Detective Grace searched the river as far as Mr Cotter's property in hope of finding the body, but was unsuccessful.
Mr Lowe, Government surveyor, arrived yesterday and proceeded to Ngawapurua to arrange with the natives for a canoe to search and drag the river to-day. Messrs Jones and Peters kindly offered the use of their boat.
It is now certain the body cannot be above ground after the thorough search made yesterday and it must be in the river. How it got there is the mystery. Some people still suspect foul play and that the body has been thrown into the river and the papers &c., thrown into the river on Friday night and that the letter found on the bridge on Saturday fell from the bundle. Were this so some traces of the deed would have been discovered yesterday, so that this view of the matter may be dismissed.
A STRANGE DREAM On the Monday night after Wlaton was missed, Miss Rees had a strange dream. She dreamt that with her father and Mr Lindsay she was walking along a road. They came to a large bridge when Walton suddenly disappeared, they knew not where. Miss Rees is therefore certain he had gone over the bridge into the river and that his body will be found in the river. Those who are sceptical about dreams must admit there was something in this as Miss Rees did not even know Walton was missing till two or three day after.
THE SOLUTION What can be the solution of the mystery attaching to Walton? This much is known - he had purchased a farm of about 500 acres near Feilding and has men on it felling the bush. He was about to leave Palmerston, as he had closed his banking account there and had written to Miss Rees that he had to go to Woodville on Tuesday and would be in Blenheim on Saturday. He did not come to Woodville till Friday. His business here cannot be discovered, if indeed he had any. He certainly spoke to Mr Birnie and Mr Bickerton, but his meeting with these gentlemen was only casual, although he did some business with Mr Birnie. He stayed in Woodville a very short time and then left to return to Palmerston. He had remarked to Mr L. D. Bickerton that he was afraid with the horse he had to meet the coach in the Gorge and Mr Bickerton told him if he left about half past one o'clock he would meet the coaches on the Woodville side of the Gorge. Walton was a good horseman and the horse must have been a very bad one of he was so much afraid of it.
Detective Grace, who has made careful enquiries, is of opinion that Walton was thrown off his horse on the Gorge bridge into the river, his horse probably being frightened at the scaffolding erected there for repairing the bridge. This theory seems now to be gaining favor. This would certainly account for the letter being found on the bridge of this is where he was thrown off and for the other letters and papers found down the river thrown out of his clothing at the time. Against this theory of Walton getting off the Gorge Bridge either by accident or design, there is the objection that the carpenters were working a the bridge and should have seen such an accident had it occurred. Of course Detective Grace's idea may be right - that these men were a good distance from where the mishap is supposed to have occurred and that they have enough to do in such a dangerous position to see to their own safety and that any noise made by Walton falling into the river either by accident or design would be inaudible in the hammering of the carpenters and the sound of the water. If Walton met his death in this way he had a terrible fall of about 80 feet and would probably be killed by the shock with the water after falling such a distance. Unlikely as an accident of that kind seems, it is possible it might occur, but if there is any design about it Walton would hardly ch hose such a dreadful place with men working all round. Of course there is the possibility of his having gone into the river below the bridge, but if he did some trace of it would have been seen.
Some insinuate that he may have chosen this as an opportunity of getting quietly away, if he had any reason of to leave the district, leaving his horse there, waiting till nightfall, throwing papers in the river at the bridge as a blind and going to say, Dannevirke and taking a train and catching a steamer on Saturday, This is, however, very improbable. Walton was a man of means and property and therefore most unlikely to leave the district where his property was, so that, though a possible explanation, it is a most improbable one. For ourselves we feel certain, all things considered, that Walton got into the river either by accident of design and in the vicinity of the bridge if not from the bridge itself.
DRAGGING THE RIVER Mr Lowe, Government surveyor, with whom Walton worked for four years is arranging for dragging this river, Yesterday several charges of dynamite were exploded in the river but without effect, in hope of raising the body. Detective Grace has again gone to search the river to-day as the body should now be afloat.

Woodville Examiner, 20 Aug 1890
The GORGE MYSTERY Little more has been discovered in connection with the disappearance of George Walton. We have seen Mr Birnie with whom Walton spent nearly the whole of the time at his disposal when in Woodville. He informs us that Walton told him his reason for coming to Woodville was that, having had a jollification at a party, he had taken the ride to Woodville with a view to getting over the effects and to be away from his companions in Palmerston, as on his return he had to leave for Wellington or Blenheim. Walton was perfectly sober and Mr Birnie saw nothing unusual about his manner beyond that of a man who had had a bit of a spree.
The letter picked up in the river on Monday was found near the lower ferry and was picked up by one of Mr Peters's family. It was a letter from Walton's father to him and puts rather a different complexion on Walton's affairs. It now turns out that Walton had not received the large sum of money which he had told his friends he expected and which they generally believed he had received. From this letter it appears he had only received £100, his father stating this was all he could conveniently send him at that time .. (£100 in 1890 is equivalent in 2009 to $17,500)
Walton also had an engagement to meet on account of his purchase at Feilding. There were only a few shillings to the credit of his Bank account at Palmerston. Whether these matters had anything to do with his disappearance it is difficult to say, but they alter the idea of the excellent position which Walton was supposed by his friends to be in. His friends and those who him best think his disappearance is the result of mishap and the enquiries of Sergeant Manning at Palmerston elicited the fact that the horse Walton rode was a very dangerous one to ride on account of its habits of shying and jumping about, so that Walton may have been thrown from the bridge into the river after all, though the men at the bridge are certain they would have seen it had such been the case.
Mr Lowe and party dragged the river on Monday and Tuesday, but could find no further trace of Walton. Detective Grace returned to Napier on Tuesday.

Woodville Examiner, 3 Sep 1890
THE BODY FOUND A report reached town just as we were going to press that the body of Walton has been found in the river in the Gorge, a little distance below Barney's point. The body has been fixed to the bank awaiting the arrival of the police. Constable Treanor has gone down to take possession of it and arrange for holding an inquest, Walton has been drowned after all. There is no doubt now that the case is one of suicide as a large stone, weighing about 30lbs is attached to the satchel evidently to keep him down in the water.
* The following significant letter appeared in the Wellington Post on Tuesday last. SIR - I am constrained to submit a few remarks re the death of George Walton. Until your last night's issue. I felt convinced that Walton had been accidentally killed or drowned. But, on reading the telegraphic account of the stone in the satchel - pointing to suicide - I am compelled to say that during my lengthy colonial experience I have never come across a more unlikely person to commit such an act. A few days before his horse was picked up he was with Walton for some hours and I must say that he was in the height of good spirits and health, looking forward at no distant date to his marriage with one to whom he was strongly attached. Others more intimately acquainted with Walton than myself may be able to testify stronger reasons than I can for the unlikeliness of suicide being the cause of death. As it is, from the very brief accounts we have had with regard to the finding of papers, letters, & c., belonging to Walton on the banks of the river, it appears to me that the assumption of suicide is very unsatisfactory. And I for one sincerely trust that before this matter is forgotten the authorities will make all due inquiries and satisfy themselves upon what appears to me the very doubtful manner in which poor Walton met his death. - W. Riley

His full story here:
The Mysterious Death of George Walton, Manawatu Gorge
https://www.familytreecircles.com/strict-71122.html