Before you travel to London it can be useful to check out whether there is a national holiday coming up or not. Here you can find a list of holidays when normal shops are closed. Restaurants are though normally open on most of these days as well.
National holidays in England and London
January 1 – New Year
March 1 – Saint David’s Day
April 23 – Saint George’s Day
October 31 – Halloween
November 31 – Saint Andrew’s Day
December 25 – Christmas
Always changing:
Easter, Pentecost, second Sunday of June