At midday a flotilla of historic vessels, leisure cruisers and passenger boats will take part in a procession on the River Thames to mark the day on which Queen Elizabeth II becomes the longest reigning monarch in British history.
This date will mark the 63 years and 216 days since The Queen came to the throne.
The procession will feature vessels such as Havengore and Gloriana, which participated in the Queen's Diamond Jubilee River Pageant in 2012, as well as the fireboat, Massey Shaw.
It will begin east of Tower Bridge at midday, with the vessels sounding their horns for one minute.
Tower Bridge will be raised in salute and as the procession passes by HMS Belfast, a four gun salute will sound and Massey Shaw will shoot jets of water into the air.
The procession will end approximately 30 minutes later outside the Houses of Parliament with a final fanfare and 'three cheers'.