You will get a better rate of conversion from the broker than from you bank - banks pad the spread on conversion in my experience.
For the benefit of anyone who passes by this thread in future: I can confirm you will receive a far superior rate from Velocity Futures Broker, than you would with a British Bank. The day in question, when I initiated the transfer, the prevailing exchange rate according to Google was around 1.6 (GBP to USD). The rate offered by various British banks ranged from 1.54 to 1.56 According to my Velocity Future account, the incoming wire transfer indicates a conversion rate of around 1.6.