This year Christmas Day falls on a Thursday. There are public holidays for Christmas Day and Boxing Day on the 25 and 26 December. Virtually everything is closed for business on Christmas Day in London. Some places, including banks, remain closed on Boxing Day (the day after Christmas).
Almost all of London's attractions close for at least one day over Christmas, and many close from 24 to 26 December, as well as 1 January.
Day|Week|Month