Brilliant - very interesting indeed.
I spent last night reading military vehicle forums about the ML James. Incredibly well documented due to the military contracts that governed their production and delivery.
Of interest to us is that MLs were delivered between 1943 and 1945, with frame numbers up to ML8500 - there were contracts to supply 10,000 but the last 1500 were not delivered to the military. ML numbers beyond 8500 ended up (mostly) on the postwar civilian market.
Now here's the interesting bit: All the ML engines (Villiers 9D) were all AAAxxxxA numbers, with xxxxx mostly between about 20000 and about 28000.
The experts there agree about the A suffix on the 9D engines: "Unfortunately records of Villiers 9D engine numbers do not appear to have been retained but it is thought that they were fitted to WD James ML's at random without any particular sequence. The suffix "A" after the engine number was a mark applied by Villiers to signify a post-1939 9D engine with the revised crankcase sealing method (the "gland" seal on the driving side), the "A" signifying "amended"."
They also suggest that, unlike the ML frame numbers, the Villiers engine numbers don't seem to appear in strict order. Nevertheless, the Waratah engine number AAA24024A is right in the middle of the 8000+ engines that went into MLs for the military, do it's likely well into wartime: 1942, 1943 or even 1944?
So, what date for the Waratah?
I've been back and searched wartime newspapers. New Waratah adverts petered out towards the end of 1941 (ignoring Ted Bailey's unchanged long-running advert in "The Propeller" claiming to have New Waratahs on hand), but there was a surprise advert from P&R Williams offering "a few New Waratah Motor Cycles" in December 1942. No mention of the model, but let's guess 9D engines.
The post war, I found an announcement of "limited quantities" of 1945-model Waratahs in September 1945 (all 9D). The "Brand New 1946 Model Waratahs" landed in July 1946.
As I see it, the Waratah for sale could be either a "1942 surprise shipment" landed in December 1942 or a "1945 model" landed in September 1945. I'd guess bikes in both shipments might look pretty prewar, with the "1946 model" having what we call postwar features - new frame, gear change through the tank, etc.
I'll try again for frame number.
Leon