Was it something like an S160 for the second world war? Don't know what number it would've had though.
One more go before I go to the pub. An Austerity Tank? I'm sure it isn't, but it must be something relatively simple I suppose?
I want to say it was a big WD 2-8-0
Was it a pannier at Swindon?
LMS were big on PR stunts, so a Black 5
A Midland 0-6-0 built at Derby?
Like Cowley I would have then guessed a Midland 0-6-0 but I guess that is wrong. So maybe the LNWR (again, PR users, normally vs the MR) but loco type no idea.
Or was it a very busy Norfolk farmer on the M&GN? :P
The only LNWR class I know are the D/Super D. But I really doubt it.