Nine teams of people are competing against each other to pull a 14-tonne, 11-and-a-half metre lifeboat, a quarter-of-a-mile, in the quickest time possible.
It is all to raise as much money as possible for the RNLI.
The lifeboat will sit on a low loader during the event, creating a massive 37 tonnes for the teams to pull through the London park.
More top news
George Michael died in December last year at the age of 53.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.