According to the Lucas parts list, the right dynamo for Cs Series is an E3L from 49 till 53, reference 20010 (plus a letter from A to K, could change from year to year), anticlockwise.
Am I right in saying that the Lucas E3L is longer than then 1945 E3HW and E3HM series that I think I may have. I've noticed that the E3L has two fieldcoil screws on the main body whereas mine only has one.
Will am E3L fit my bike or do i need the shorter E3H series?

thanks
Tony

Lucas E3H model 200424 Anti-clockwise direction taper shaft is the one from my Lucas book.

For the 49 onwards model the engine breather was moved to allow for the longer E3L dynamo. The end cover was always close with the E3L.

Good info, thanks Owen.

I think you have the correct E3H short dynamo for a ‘45 bike.  The longer E3L might not fit if the breather is going to foul it.

I took my dynamo to an electric motor rewinding workshop and some of the grey bearded blokes sorted it out pretty quickly and cheaply.  It is just an electric motor in reverse basically. 

The corroded case is just cosmetic.  A wire brush and some filler will make it look pretty. As long as the case can earth to the engine body you’ll be right.

I have a E3HM-LO dynamo spare if that is of use?

The bodies were originally nickel plated, but you could do with a nicer body for that. At least with paint, you can put lots of high build primer on first. Ron