Thanks guys much appreciated, bulbs are standard, lamp contacts seem fine. Might moisture getting in there cause something like this? I checked the fuses (though they look Ok I'd say they are very old). The pics are useful, wonder where I can get a similar fuse holder this side of the water? I did uprate the regulator at one point in order to boost the battery charging. I'm wondering if that might have anything to do with it, doubt it though as whenever the signal regulator went, it was on a short trip.
Cheers,
Simon