Mandatory Credit: Photo by Guy Bell/Shutterstock (11852086c) River Police boats are on station to stop traffic on the River Thames during the 41 gun salute at the Tower of London. The White Ensign flies at half mast on HMS Belfast in honour of Prince Philip, Duke of Edinburgh, who died yesterday aged 99. White Ensign at half mast on HMS Belfast for Prince Philip who died yesterday aged 99., HMS Belfast, River Thames, London - 10 Apr 2021