At the river Pool in Lewisham, south east London, the mayor of London helped to remove a scaffolding pole, a shopping trolley, an old car battery and an abandoned umbrella.

Mr Johnson was also unfazed when he found one of the deeper parts of the river and fell into the water up to his chest area, he was helped up by volunteers, and after a short pause carried on clearing the waterway.

He carried on helping as volunteers pulled out bags full of himalayan balsam, which was introduced by unknowing Victorians, and has had a devastating impact on natural plants as it takes over vast sections of riverbank.

The mayor was joined by local people from the Quaggy Waterways Action group and Thames21 the charity that organised the event.

Mr Johnson said: “Volunteering is good for individuals and great for London in tough economic times.

“By giving your time, whether a one-off few hours or a regular commitment, we can both help to make the capital a more civilised, pleasant place and reap the rewards of putting something back into the communities in which we live.

“I want to give a great big pat on the back to the unsung army of people who are already volunteering in London, and urge more people to have a go.”

Joining the mayor at the river Pool was Debbie Leach, chief executive of Thames21, who added: “We have been delighted to work together with the mayor today to clear up this wonderful river and to encourage more volunteering in London.

“We rely on 4,000 volunteers each year to make a difference to London’s waterways, making them places for all to enjoy and appreciate.”

Luke Walsh

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