I found the leak.

[sidpinup]

If anyone gets water coming in the drivers footwell as I was this may be the answer. It's been driving me mad for a few weeks. Every time I went for a drive in the rain water would collect behind the dash and drip onto my feet and carpet but also the fusebox. I discovered it was the bonnet release cable tracking water through the bulkhead grommet. A little bit of sealant fixed the issue.

[SergSC]

Cool Thanks! Also get water into my fuse box but have not been able to find the source, I'm off to do mine now

Also had a little puddle in the floor of the control box cubby hole in the pass footwell, this seemed to be dripping along the wires coming from the bulk head grommet at the top of said cubby hole, this grommet was loose and definitely not remotely water proof... stuffed it with sealant. This may well be why the alarm was going off for no good reason at the same time as fuse box and dash crazyness... its probably what killed my immobilizer and left me stranded at the petrol station.