There was an exhibitor (a Laurie Maunder) at the CMRA Exhibition at St Albans early this year who had made his own versions of these wonderfully eccentric locos. He'd been to the original 'Far Twittering and Oystercreek' 15inch gauge minature railway in 1951 at Battersea and had collected a book of card models to make up. He had never done so, but had then used photocopies of the printed book to use as templates for his models.
Regretably my parents never took me to Battersea although I can recall visiting the South Bank 'Festival of Britain' exhibition in 1951 and getting rather tired - well, I was only 5 years old at the time!
Regards,
John Webb
PS as they are 1951 vintage definately early BR - but like the Talyllyn Railway clearly not included in the 1947 Transport Act as a constituent of BR!!