Jiri has a flat tank frame, number 24809 for sale SOLD. Simon: "Difficult to be that sure without checking the Records although obviously a sidevalve machine. It is clear some tubes have been cut/bent/re-fixed and I assume this was to fit a saddle tank at some stage. The long tube under the gearbox lug is to carry footrests, brake pedal etc and although this was discontinued on the 1926 run of the mill bikes like Model 18s or 16Hs etc., I have a feeling it was continued on a few odd machines like Big Fours for a further year."
Contact vintagenorton.com for Jiri's contact details. For those looking for a challenge there is also a 1925 Model 18 cylinder and head for sale on eBay (below).