UPDATE 27 December : Sold for 375GBP
http://cgi.ebay.co.uk/Garden-gauge-63-5mm-MIDLAND-1F-electric-loco_W0QQitemZ330387912884QQcmdZViewItemQQptZUK_Trains_Railway_Models?hash=item4ceca778b4
On Ebay (from same seller as the GWR 45XX) is this Johnson 1F MR tank (in LMS livery) assembled from a GRS kit.