As I suspected - after nearly two months of running without a problem with lights the main fuse under the bonnet, which was the problem I found has now blown.
When I tried to replace the fuse, the replacement fuse blew within seconds. I tried a piece of wire across the terminal and the wire melted and I had some thing burning behind the dash.
The current between the fuse terminals seems very high and live without the ignition on.
I have been driving in some really rough wet weather over the last few days. My horn came on and stayed on yesterday after some deep water. I disconnected it and dried it out and is fine again now.
Do you think my light fuse problem is water related? or any other suggestions please.
Thanks