Yeah - as I thought - regisrations on Intersango are closed. So.......
Question still remains - how - if - anyone wanted to change BTC into UK fiat (sterling) could they ?
Set up an account with Bitstamp, sell BTC for dollars, withdraw using SEPA transfer. They convert from dollars to euros, then when the money reaches your UK account it will be converted to sterling. Everyone takes a % along the way so do some maths. You might find it cheaper to set up a Euro account with a UK bank for a monthly fee.
So yes, it is possible to change BTC into sterling, it is a fairly long process.
Another option is bitcoinfridge, who supposedly buy BTC in sterling. However I never got a reply from them.