See Sligo, Michael Farry
Above is a short article on Watt(s) from a local history published in 1997 "In the Shadow of Carran Hill". The graveyard, called Corrig in this article, is in the townland of Carrownyclowan which is near Drummacool on the R284 in SE Sligo. After the body was discovered Alec McCabe, the only one of the four mentioned in the article alive at that time, wrote a letter to the local paper details similar to what appears in the article.
Executed around Jun 1921. East Yorks Regt probably stationed in Drumdoe at this time, and Bedfordshire at Boyle (I can find deaths of the 3 Lt Watt in Bedfordshires with MIC in TNA so he does not seem to be one of them). He is not in Auxiliary Roll, so does not appear to have been in ADRIC
At some stage the 2nd Suffolk Regiment had their H.Q. at Boyle, as did 1st Leicestershire
There are 4 possible in 1920 Army List (if his name was actually John Watt) But I cannot tie Gordons or Black Watch to the area. Further TNA has around 20 John Watt(s) plus many with only initials.
Around this time the IRA in the Conway's Cross/Geevagh area were contacted by a British soldier who also claimed that he had deserted. The IRA were sceptical and the man was court martialled in Gleann Hall. Among the officers involved in the court martial were Alec McCabe, Tom Duignan, Tom O'Donnell and M. J. Marren. The soldier, a lieutenant from the forces at Drumdoe near Ballinafad whose name is given as John Watt, was found guilty of being a spy and was executed. He was buried in a bog and his body was accidentally uncovered by turf cutters in May 1962. It was re-interred in Carrick an Teampall graveyard, Conway's Cross
WS 1312 John Joe Dockery, Ballymote, Co Sligo, 4th Battalion Sligo IRA, Intelligence Officer. In June, 1921, it was reported to me that some soldiers had deserted from the British Army unit stationed at Boyle and were knocking about in our area. One of them was arrested by Volunteers from the 5th Battalion near Riverstown. I was summoned to act as a member of the courtmartial. Sufficient evidence was available to convict him as a spy and he was sentenced to death. The sentence was duly carried out. He admitted that he was a member of the British forces; he stated he was a private soldier; he was, in fact, a commissioned officer in the British Army with the rank of lieutenant. His name was Watt. A Question was later asked In the British House of Commons as to his. fate. This gave us the facts as to his identity and confirmed our earlier decision.
Michael Farry who wrote "Sligo" then contacted me with an update I have located the grave of John Watt! Yesterday I searched for Corrig graveyard and found it close to St John's Well, near Conway's Cross in SE Sligo. It's a small graveyard, well kept, extended in the last twenty or thirty years with quite a number of unmarked plots. I called to the closest house, told them I was a historian and what I was looking for and they knew the story of John Watt. They hold the register of burials and we found his burial entry. They also said they knew where the unmarked grave was. We walked up to the graveyard and they both agreed on the plot. It had been beside the west wall but the wall has been removed and the place extended so there is an empty space on the left. I have attached photographs of the register entry and the graveplot.This link locates this the place on Google maps. It's actually sad to be there and realise that no-one of his family ever knew where he ended up, in a remote Irish graveyard among Kelly and McDonaghs.