Dead electrics.

Now what have I done..!.?.
 I was just finishing up putting everything back after re checking the valve clearances and re torquing the head after running in my new piston rings after 500+ miles, when I remembered my front brake light had stopped working on my last ride.. So I had a quick look and also noticed the front brake lever nut was loose too. I grabbed a socket to re tighten it and accidentally touched both terminals of the brake light switch. There was a little click like a fuse popping and now I have no electrical power at all apart from my manual fan switch still works.

My fuses are are all good in the fuse box. Unless there is a hidden fuse somewhere I don't know about? I've started pulling things off to have a look. but before I reach total strip down point again I thought I'd better stop and ask...I had a look at the wiring diagram but only managed to find, that I now have a splitting headache.  Any pointers would be great thanks.

Did you leave the Main Switch off after opening the seat to check the fuses?  
 

Good thought  but unfortunately not.... I made that mistake the last couple of times...

Something else has happened here and I don't believe that bridging the front stop light switch caused the problem. That switch is normally open and bridging it would have powered up the brake light, unless you happened to bridge the power feed for the brake light to ground, then you would have blown a fuse. That circuit is fed from the 10A fuse which has the brown/white stripe wire coming off of it. 
If you've lost all of the power, then that circuit is the 30A fuse, but it's not associated with the front brake light circuit so, you may have inadvertently caused an open ground circuit somehow. 
Armchair diagnoses can be a real bitch. Just trying to provoke thought here. if all of the fuses voltage check out fine and you have no power, never forget the ground circuit that returns all of the available power back to the battery.

Thanks.  I thought that bridging the brake light wires would have just made the connection and switched the brake light on. It's strange.
There seems to be no power to the fuse box at all, except the "Main" and "Fan".
I tested as far as the ignition key. So when I turn the key to on, power then flows through the first muliti connector behind the headlight. But from there it goes in to the wiring loom. I'll have to see if I can follow it to the next place.

Good thought to double check the grounds. I'll try and follow that and check as many as possible.
Electrical gremlins are the worst. That's why I have no modern vehicles at all.. then again you get corrosion instead.

"........now I have no electrical power at all apart from my manual fan switch still works. "

Because you were working on that side of the handle-bars you may have inadvertently turned off the KILL switch ?