I've posted this on RMWeb as well, but you can never have too much expertise....
The rebuilding of a Londoncentric 3F gets more devilish with every turn. Having refettled the underwear (including an errant slippery wheel in the quartering and a homeless Mashima 1620) I now find that the beast in question (47307) is one of the screw reverse variants. It has no keyhole access for the rear sandbox, and it appears from http://www.railuk.info that it was one of a batch built by Hunslet.
I have several pictures of 47307 from those fine people at The Transport Treasury, and these show a cylinder lying on top of the driver's side side tank (RHS from the footplate).
Does anyone know if this tank accompanied the screw reverse, and does anyone have dimensions or a decent picture of the pipe run? I figure it was just a reservoir...
Oh.... and does anyone know of a suitable source of a casting for the screw reverse wheel in the cab? I think Comet or Gibson do one, but IIRC its for an 8F..... any chance they're a 'one size fits all'? Push comes to shove, I'll fettle one.
Any pointers towards any articles on these engines would be good, too
Cheers
Jan