The bacteria, which can cause serious infections, was discovered by the Henley and Marlow River Action group.

‘High E.coli levels discovered in Thames’ ahead of Henley Royal Regatta

The drone, which weighed 28kg, was filming the Regatta from the air when its battery ran out and it crashed into a boat.

Henley Regatta drone crash could have killed someone, report finds

The event, which showcases rowing over a six day period, will run from Tuesday 28 June until Sunday 3 July.

Women are now allowed to wear trousers at the Henley Royal Regatta for the first time in its 182-year history. 

Last year was the first time in the event's 182-year history it had to be cancelled, apart from during the two world wars.

The world-renowned rowing event was due to take place on 29 June to 4 July on Henley-on-Thames.

Rowers and spectators alike descended on Henley-on-Thames today for the start of the five day Henley Royal Regatta.