Catesby resided at "Belmont" Inn, Fairfax Co., VA. The current address of "Belmont" is 10913 Belmont Blvd. About 1728 he came to live on the Potomac as clerk of Stafford Co. He was the first clerk of Prince William court at the organization of Prince William Co. in 1731 and held that position until 1746, then deciding to retire. Also he had been the first clerk of Fairfax County. In 1734 he purchased property in Fairfax from Thomas Simpson, being 250 acres on the shore of Occoquan. Then he added 300 acres on the north, and then nearly doubled the plantation in 1746 by adding a tract to the east. Ultimately his land extended eastward to Kanes and Mill Creek. Like most substantial men of his time, he dabbled in real estate and patented in Old Prince William no less than 67 tracts of land, totaling 39,349 acres.
When Dr. Cocke died, Catesby trained under John Carter, who succeeded Dr. Cocke as Secretary of the Colony. On 24 Dec 1724 Carter writes from Williamsburg that he is appointing Mr. Catesby Cocke to succeed Col. Mason as Clerk of Stafford Court. Carter says of Catesby, "His having been a long time in my office and thereby made capable of such business and being the eldest son of my predecessor are a great inducement to me to provide for him before any other person." The following refers to Catesby as an attorney: "Recorded Pr. Wm. Co. A/44-49 appoint Catesby Cocke, Gent. of Pr. Wm. Co. my lawful attorney to relinquish my right of dower thirds in 500 acres on north side of main run of Occoquan River called Broad Run in Pr.Wm.Co."
Overlooking Belmont Bay, the plantation house "Belmont" remains today on Mason Neck, an historic landmark of the colonial era, and doubtless one of the oldest dwellings in Fairfax County. Reportedly the original house contained five rooms with cellar and is believed to have been built by Catesby Cocke about 1730 when the first Prince William Courthouse was established on the Occoquan. The house appeared on a 1737 map of the area. Catesby Cocke served as clerk for Stafford, Prince William, and Fairfax counties until 1746. In 1742 Cocke sold "Belmont" to Edward Washington.
Letters written by Catesby Cocke to his sister Mrs. Pratt:
"Stafford 17th ffebruary 1724 My Dear Sister I shall be very glad when this shall acquit me of a promise I made of writing to you when we parted that is, in short, I shall be glad when you receive my Letter that I may sooner have an answer but you must Excuse this roundabout way of writing as coming from a very barren place and where without that and indeed with it I shall hardly be able to make my Letter as full as the Friendship between us requires, which by the wayyou may take as a Hint of what I expect from you. / I believe you'll think it strange that your brother of all people in the World should turn Critick & in Dress butthat I'll leave to your own Judgment till I shall see you to justify my self in some prodigious accounts of what my Travels have afforded and to that Time I'll leave it for if the picture should be seen, it would too easily discover the Original & the Carriage of Letters in Virginia is well known not to be always safe tho I am at present as innocent of the person that may carry this as you are and I'm satisfied always have been of those I just now spoke of. In my journey to Westmoreland I lay at Colo. Tayloes and there saw Mrs. Chiswell they live in a very genteel manner and both Tayloe & his lady are as agreeable people as I know and seem to be as happy in each other as their Neighbors are in them. They have three Children, the youngest as fine a Child as ever I saw & a very pretty well-behaved Girl which I am certain you of all people in the world will allow the surest way to make harmony last. Mrs. Mason sends her service to you, she has a fine prating Girl & a Boy about the age of Billy. If this should light into other hands I shall be taken for a fine gossip but the pleasure I know you have always taken in such discourse since you have been a mother makes me mention these things and as such I am apt to think you'll receive it, tho' I must own the same from you would give me the greatest satisfaction whether it relates to our own family, which I desire you would gratify me in by a full account of my neices and nephews. / As soon as I come hither I heard from people who pretended to know it that R admires itself beyond any Letter in the alphabet tho I cou'd have told 'em theres another with the same sound which might possibly in some measure take from it the admiration of its own pretty self. I expect to have the issue of that and the things of like nature. / My service to Mr. Secretary and all the family. / I am my Dear Sister's affectionate Brother & most obedient and Humble Servant. / Catesby Cocke"
Wednesday 22-ffebruary, 1724 I received last night Letters from my Mother & Sister Nanny which I take for your Reason of not writing at the same Time & I hope hereafter will be received as a good excuse for me when I only write to one of the ffamily tho' I shall take all occasions of writing to more when I can furnish my Self with Matter. I beg you would make my excuse to Mr. Robertson & my Sister Nanny for not writing it now being Night and to Morrow I shall set out early for Westmoreland when I expect an Opportunity of sending this to you. / I heartily pity the Inhuman usage of some people ab't 120 miles from hence but other people best know the Cause-and to my Dear once more bid you heartily farewell & as before. C. C.