DDK - Die Deutschen Klassiker

Went for a drive this morning, everything fine, came home and reversed car on to drive. Left it for 15 mins then attempted to reverse it into garage. Wouldn't start, total electrical failure, had a blown fuse (3rd from left.) Had a spare, fitted it, no problem, reversed car into garage, everything working fine. Turned off engine and turned on again, all electrics fine.

However...

This is not first time this has happened.

A year or so same fuse kept blowing when selecting reverse gear - caused by reversing lights short circuiting (?)

Just had the car serviced by Roger Bray (he did the original restoration) and asked him to look at this but said it was now fine.

Anyone else had similar problems? Any advice would be great, although I have zero mechanical/electrical capabilities.

Re correct replacement fuse:

I've seen online Littelfuse 36VDC 8A topedo. Is this correct and do you know any good suppliers?

The switch that operates the rear reversing light bulb in the middle of your shine down holder is in the tunnel running between the front seats. As you operate the gear lever into reverse it pushes against the the plunger type switch. Maybe there is a short in that switch with a dodgy wire? I believe the fuse 3 on the pre-a also covers the dipped headlights. Not so sure on that though.

The fuse that is a normal white 8 amp? I don't recognise your version description.
Fuses blow for a reason it has to be checked out. Maybe someone with a pre-a can help. My car is an A version.

For the car not to start though when that fuse blew I would get a check done.

Needs a meter check I reckon. Hope you find the problem
Roy