This type of dynamo fitted with a set of points on the end was a fairly common fitment in the 1930's. It enabled manufacturers to convert an engine designed for magneto ignition to coil ignition simply and cheaply. Several makers used it. Royal Enfield and New Imperial immediately spring to mind as I sit here. Components are still fairly easily found.
There is nothing inherently wrong with the idea, the major problem from a modern day usage point of view is the low output of the dynamo. It was barely adequate for battery charging and lights when new. It goes nowhere near meeting modern expectations for lights, stoplight, indicators,etc. Its no great problem, you just have to be aware of it and be alert for signs the dynamo output isn't keeping up with battery usage. Nor should you expect bright white lights, an interesting shade of yellow is more like it.
The only other problem I experienced with a Royal Enfield fitted with this system was poor oil sealing between the engine and dynamo so that the dynamo had a tendency to get drowned with oil and stop charging. As I was a very green and very broke teenage apprentice at the time I suspect I was the major source of the the problem as I didn't have a clue what to do about it so merely wiped the excess oil off and kept on riding until it happened again. I never did anything to actually cure it.
Lucas did a convenient booklet covering how to look after this sort of stuff, "Instructions for Lucas Electric Lighting & Ignition Equipment for Motorcycles". It covers your Raleigh & Sturmey Archer engine very nicely and as Justin says above, the VMCC Library will have a copy.
Cheers,
