Maybe
"...... the banks and other financial institutions must report all "suspicious transactions". These include the making of unusually large cash deposits - that is, deposits larger than �10,000 - numerous deposits and withdrawals of cash, using night safes to make large deposits of cash"
http://www.seangabb.co.uk/pamphlet/monlaund.ht m
But probably not if it is a one off. The Inland Revenue will already be aware you have this money as you pay income tax on it, or have signed the relevant forms stating you shouldn't.