TR4A Distributor Question

["The Browns" <thebrown@scci.net>]

I just bought a TR4A frame and engine plus a lot of parts from a fellow who
after 10 years decided not to rebuild the car.  He disposed of the body
because it was badly rusted.  He is my question:  The distributor is Lucas
model without any vacuum advance.  The only numbers are 23D4 and 40819K.
Any ideas about what it is or how it could work on this Engine SN CT72857E?
D. Brown