Sorry for all the confusion on the symptoms of what’s happened. I tried all the suggestions and the system was tripping the breaker. It seems that whoever installed the panel took the live feed and powered the bilge pump from this and the bilge pump breaker that was being tripped when I turned on the ignition.
I had to call out River Canal Rescue as I couldn’t get to the bottom of it. The engineer had a good look around under the engine with his camera and discovered that the wiring loom around by the starter motor had melted and fused all the wires together, to add to the horror, the 40A fuse had melted the pins together and was no longer a 40A fuse but something with a much stronger rating. So everything was tripping because of the melted loom. I have to now sort out getting a new loom made up.
The 40A fuse issue probably contributed to it. I’m now wondering if the key barrel had shorted on starting the engine and the stuck 40A fuse caused it to heat up the loom and melt it.
Thanks for all your help and again I apologise for the confusion, it seems there are a few factors at play here.