|Cemetery notes and/or description:|
The cemetery now physically exists in Lancaster. The reason for the confusion is that in 1901, to make way for the Wachusett Dam in Clinton, the people in Clinton's St. John's Cemetery were dis-interred and re-buried in Lancaster. So, indeed at one point, there was a St. John's in Clinton, but not since 1901.
For more information, see David Lambert's A Guide to Massachusetts Cemeteries.