406 Strange behaviour of instrument display

[Peter.N.]

I went and had a look at a 'Y' reg executive estate today, its about the same age is my present one but a lot less miles. The speedo display is permanently lit showing 0000 even with the key out, if you turn the ignition on it reverts to normal operation and it starts OK. Everything seems to work alright but of course it will run the battery flat if left. Any ideas?

Thanks, Peter