The Sludge, thanks for that. There's obviously something not right somewhere then, because I'm doing it exactly as it says. On the drivers side inner light, I've got two wires coming off it, and one I've connected to the blue long wire coming across from the other unit, and the other I've made an earth lead for, and attached it to the bodywork. Is that right?
Does it matter which lead goes to which wire on the inner lamps?

I've got nothing from either of the two inner lamps though, and I've been trying allsorts today. I wonder if the relay's blown or something.

Any ideas anybody. That'll teach me to buy them secondhand! What a faff!

I assume you can't get these relays easily can you?