why can't normal regulated currency exchange houses such as FairFX or CurrencyFair just add BTC as a new supported currency?
Mainstream fx exchangers won't look at a currency which does not have a valid ISO code, which is the main reason I have been pushing XBT for the last 6 months. Fortunately xe.com recognize XBT and Bloomberg are using it internally. Once Bloomberg make their bitcoin page available to all subscribers then there is a real chance that mainstream fx companies will see it as legitimate and start supporting bitcoin.
Max Keiser talked about plans for a London bitcoin exchange, but there doesn't seem to be any news on it.