I'm wanting to replace my screened ignition system for a civilian 12v Lucas distributor. I understand the military system has a dropper from 24v to 10v. On the web I'm finding conflicting info whereby some claim the existing dropper (24v to 10v) is fine for the 12v coil and distributor, others saying a new (24v to 12v dropper is needed). What is correct? If I need a new dropper, what parameters should it have?

Thanks

You will not find an off the shelf 24v to 12v dropper.
The issue of using replacement droppers & 12v coils is covered on pages 87-89 of this:
http://hmvf.co.uk/forumvb/showthread.php?53479-Bright-Sparks-Latest-Update

thanks fv1620. I've read those pages and will have a think. I've heard of many people using the droppers and just converting the engine to 12v. Was on the phone to a mate who did his 101...I'll give him another ring.