Athlete Christine Ohuruogu was at City Hall on Thursday morning to unveil a temporary addition to the riverside path at More London: a temporary running track.
The dedicated 500-metre running lane was marked out on the Thames Path between HMS Belfast and Tower Bridge.
The gimmick was intended to promote Cancer Research UK's Run 10k series of fundraising events.
A poll of 1000 runners carried out for the charity revealed that 27 per cent found dawdling pedestrians to be a nuisance.
The survey also revealed that a quarter of runners are perturbed by motor traffic they encounter along the way and 20 per cent say cyclists are one of the factors that bother them most.
The stunt comes in the same week that the tension between pedestrians, runners and cyclists on the SE1 riverside was brought into focus by the publication of new proposals to enforce a cycling ban on part of the South Bank in Lambeth.
"Each year it is estimated that that as many as 1,500 deaths from cancer in the UK could be prevented if people kept more active," says Natasha Dickinson from Cancer Research UK.
"In fact our survey also found that almost two thirds of recreational runners (63 per cent) in the UK don't know that physical exercise can help reduce the risk of cancer.
"The charity's Run 10k series is a great way to start running by setting yourself an achievable goal.
"We have Run 10k events taking place in wonderful locations and city centres across the country and this year we are urging everyone to enter, raise money and Run 10k to help us save more lives through our groundbreaking work."
London's Run 10k events will be held in October at Victoria Park, Crystal Palace and Hampton Court Palace.