If you want to see 'Issin Sid then you need to get yourself to a Statfold barn Railway open day. See http://www.statfoldbarnrailway.co.uk/news.php
for the dates of the 2016 open days.
If anyone has not seen 'Issin Sid, this is the wee beastie.
It goes for about 400 yards on one filling of air, but has now been given a compressor in a mine tub to drag along so it gets let loose on the Statfold main line.
I reckon something like a Hornby (ex-Dapol) L&Y "Pug" or the High Level Kits chassis for the "Pug" could do as the under-pinnings for a Gn15 version. There's a Hornby "Pug" in my cupboard, hmmmm............