This was one of Scan Tester's songs- 'the 'Lakes of Coalflin'- all about Willie Leonard.
As well as a great Sussex concertina player (1887-1972) he sang the occasional song- read Reg Hall's excellent biography/LP for more on Scan-
'I NEVER PLAYED FOR MANY POSH DANCES'   (now on CD)

the other song he had was 'I wish they'd do it now'.

Lough Sheelin is a fair sized lake in north central Ireland & maybe the original of 'Shillin'?