Hi Guys
Latest theory is that the Alternator shaft broke, throwing the pulley on to the belly-pan.
Lack of tension in the belt stopped the water pump operating. I then had a 2.5 litre turbo-kettle!
I was trying to work out what the 'clunk' had been, and why the sediment light had come on (the charging light didn't come on which is weird) when I noticed the temp gauge going ballistic and stopped ASAP.
The coolant alarm never had a chance to work (though it beeps like a b####r now it's empty...) before it had dumped the water out the overflow.
They were going to do a pressure test first, then a new alternator (ouch...) then run it up to see if it survived.
It's such a fab vehicle to drive I'm really torn between getting it sorted and pushing it off a cliff - not for the insurance, just for revenge
Thanks for all the replies - I posted here in frustration really but a lot of you have been through this.
Truth is, I'm doing 20K (+) miles a year in the Bongo and need something else to do the hard miles.
I'll keep you informed.
Jon