Dave Osborne gurgled happily, sounding much like
they were saying:

I'm thinking of building in one of those Lidl battery chargers in the
old car. So it can be left on float when not in use. The mains lead on
those is only two core and the case plastic. I was considering a
Buccaneer weather proof mains connector mounted in the body below the
rear bumper. Should the car body be connected to mains earth?

No. If the battery charger is double insulated, then the only issue is
preventing the chassis becoming live from a fault on the mains cable.
Cover the mains lead in plastic conduit and ensure that it can't chafe
or snag on anything. Make sure you plug in to an RCD-protected supply.

Or do it the other way round, and plug the low-voltage into the car,
keeping the charger.

Motorbike Optimate-style.