As I said earlier, a number starting 526 must come from contract S1050 ... 9000 bikes which all have a 7 digit number. I think it would be near impossible to get the frame number without those missing numbers.
But the sequence is:- Frames 48060-57059 were allocated census numbers 5255460-5264459 and usually in numerical order. So if you take the first number that starts 5260000 from the last number, you have nearly 4500 bikes to chose from
However I think it's quite nice to know the period it was supplied which I think must be in late 42 or early 43. I'd guess your picture at somewhere between 43-45
Maybe someone else could confirm my calculations? Ron
In my opinion the number on the petrol tank reads C52603XX, the last two digits are obviously unreadable. Ron is correct that frames 48060-57059 were allocated census numbers 5255460-5264459 (contract S1050), and for the S prefixed contracts the last two numbers of the census number corresponded with the last two numbers of the frame number. So we're looking for frame number 529XX... I think John T is keeping a Register for the WD Matchless'...? John, any survivors between 52900 and 52999?