classic motorcycle forum

If it's the girder-forked look that you're after, then probably the ex-War Department models offer the lowest prices and the best spares availability. Many of them have been 'civilianised' or can be made to look pretty much like their pre-war ancestors.

Triumph's Coventry factory was bombed in 1940 which rather drew a line under the pre-war models and Rudges haven't been made since then either.  In WD circles, Triumph 3HWs are thought of as a little difficult for parts but they're far easier than any of the makes or models which ceased with the 1930s.

Only you know whether you truly want something that relates to the the 1930s or you're just after the fun of a rigid 500cc single with girders. If the latter,  then a BSA M20 is probably the most accessible, although a Royal Enfield WD/CO could be cheaper (and it's Overhead Valve).

The registration number is a Chester series which was used from 1904 to 1936 which doesn't tie the year down much. Is it an early 1930s Sunbeam ? Possibly a Model 10 ?

It puzzles me that this ignition is sold as a 'one size fits all'. I'd understood that Triumphs and Nortons (for instance) required quite different advance curves.

It's got Jubbely forks and front wheel. I've seen a few fitted with a Navigator front end but only Ogri's mate Malcolm would fit the Jubilee bits to a Navigator.

Do all those lugs mean it started off as a 'deLuxe' with Norton's version of the bathtub ?

The Vintage Motorcycle Club have all the Amal production build cards and from memory, these include industrial and other applications, not just motorcycles.

It might be worth giving them a ring. If they have the cards for the Dennis carbs then these will normally detail which standard parts were used to build the particular option.

C61333 was indeed part of a batch of WD serial numbers issued to impressed machines of various makes. (C61001 - C62360).

It dates from the period when RASC were responsible for all 2nd echelon vehicles. The majority of these were dealer or factory stock purchased during 1939/40 and were generally fairly new. The machines taken on by RAOC for the front line units were referred to as 'Local Purchase' which is perhaps a more accurate description of the arrangement.

The vacant front and rear number plate positions were often used for the serial number between the discontinuation of civilian registrations at the outbreak of war and the move to instructing the factories to apply the number to the fuel tanks during 1940-'41.

This bike has the Lucas MT1130 rear lamp which was used by Ariel and BSA and generally seems to have been introduced during 1939 for the 1940 model year. It seems to have been given an all over coat of paint but it has burned off from the chrome exhaust (Is it a twin-port, by the way ?). It's quite unusual to see a 'name' painted so prominently on a motorcycle.

His cap badge looks to be RASC (Royal Army Service Corps) which fits with the number and type of machine. It's a nice sporty mount. I bet he cursed when he had to hand it in for an M20 !

I read somewhere, and it seemed to make sense at the time, that the change to an alternator with longer crank and altered weight distribution around the same time could have been responsible for a change in handling.

The fact that Manxes were wideline is always going to make the Wideline style more desirable.