Blue Peter action woman Helen Skelton has become the first person to walk between the chimneys of Battersea Power Station on a high-wire.
The 27-year-old covered the 150-metre stretch above the landmark south London building in just 11 minutes.
She was 66 metres up for the Red Nose Day charity challenge, which was delayed by 40 minutes because of high winds.
But Helen completed the task at a steady speed despite her eight-metre long balance pole swaying in front of her.
The BBC children's presenter was inspired to do the stunt by the documentary Man On Wire, which shows Frenchman Philippe Petit walking on a tightrope between the twin towers of New York's World Trade Centre in 1974.
She had been training in France in recent weeks, which she described as "really intense" and "physically exhausting".
A safety device attached to her in case she fell was not needed as Skelton made no slip-ups on the 18mm thick wire.
The challenge will be shown on future episodes of Blue Peter.
Anyone wanting to support her fundraising feat for Comic Relief can go to www.rednoseday.com/girlonwire.