RR Classic - Earth or Short?

I have a problem with my girlfriends Tdi Classic, which was laid up for a while but is now back in service, however during the summer months the problem wasn't noticed as it was only used during daylight, but now the clocks have changed it's gonna be a big problem.

In going to use it last night she found that it started fine and the headlights came on as usual, but as soon as she released the handbrake the headlights (and dash lights) dimmed to the point of being unusable!

My guess is that it's an earthing problem and that another circuit is 'borrowing' the handbrake switch's earth when it's closed, and that it's then struggling to earth once the handbrake is off? Either that or releasing the handbrake induces a short somewhere and the lights lose power?

I have already cleaned and remade some of the engine bay earth connections after starting problems when getting it back on the road.

Anyone experienced something similar, if so what was the cause? All suggestions that don't involve boxes of matches welcome!

battery needs to be well earthed to chassis engine and body,body earth would seem poor,normally near battery

Not a short or you would have melting cables, I think you have provided the right answer.

There are cases of the handbrake cable shorting out on something....generally means engine earth strap is in need of attention, not sure if this fault affected only Classics..Only P38's or if it was common to both....but I think Dta is right...check engine earth straps.

Thanks chaps, looks like I'm on the right track already, so I'll just have to work my way through checking and cleaning up the rest of the earth points.

or evn double them up with some new ones.