Other kinds of checks
If you deposit any other kind of check (a $U.S. cashier's check or even a sterling draft drawn on an American bank in Britain), it could take as long as three to six weeks to clear and have the money credited to your account. This is because Bank of England regulations require that all signatures on foreign checks be validated prior to the release of the funds. A sterling draft drawn on a London bank can sometimes be negotiated more quickly because the reserves are in escrow and the signatories are known. Any other kind of check must be sent back to the U.S. for signature verification.
Check with the cashier on the waiting period before funds are available. The period varies depending on the bank you are using, but be prepared to wait between five and 14 days.
I see. I didn't realize it was such a hassle to cash a U.S. check in the U.K.. Sorry about the bum steer.