Three intrepid cellists are playing at the top of their form on Britain's four highest peaks to raise money for charity.

Last Monday, Jeremy Dawson, 32, James Rees, 28, and Clare Wallace, 48, all from Sheffield, Eng., scaled Scotland's 1,344-metre-high Ben Nevis. After a climb of more than 2.5 hours, they conquered the final ridge and gave a short concert.

Climb Every Mountain from The Sound of Music, of course, was part of their repertoire. So was an arrangement of Lift Thine Eyes to the Mountains from Mendelssohn's Elijah.

On Thursday, they climbed Scafell Pike (978 metres) in England's Lake District, where they entertained surprised hikers.

On Sunday, they hit the high notes on Snowdon (1,085 metres) in Wales. And, on Wednesday, they plan to climb Carrauntoohil (1,038 metres) in County Kerry, Ireland.

"Mountain climbing with a cello can be demanding, and adverse weather can sometimes cause the ascent and descent to be dangerous, but we are undeterred," Dawson told Britain's Daily Post.

On the group's website, extreme-cello.com, Dawson said the idea of Extreme Cello concerts was born when the cellists watched the sport of extreme ironing on British television.

This involves contestants ironing clothes in different locations such as on mountains and underwater. They are judged on the extremity of the location and the quality of the ironing.

When the cellists heard that a Sheffield public school needed money for its music program, they decided to take their cellos to different venues to help the school out.

"Since the cello is a large instrument, this gives the venture an added complication, but at the same time a far more visual impact," Dawson said on the website.

But, unlike extreme ironing, the Extreme Cellists do not compete. Their events, rather, are collaborative musical, visual and physical experiences that are supported by individual and corporate sponsors.

The first Extreme Cello challenge took place in May 2003, when the trio played in six locations in the Sheffield area and raised £1,800 for the public school.

Two years later in 2005, they picked up their cellos again and walked 72 km from Manchester Cathedral to Sheffield Cathedral, raising more than £2,500 for Sheffield Cathedral.

In the summer of 2006, they played on the roofs of all the Anglican cathedrals in England — 42 cathedrals in 12 days — and raised £5,120 for Shelter, a British charity that helps the homeless, and Aspire, a spinal injuries charity.

Last summer's challenge involved giving a short performance on each of the streets on the London Monopoly board on a single day. It was intended to raise the profile of, rather than money for, Aspire.

This year, the group hopes to raise £10,000 for Aspire and for mountain rescue teams.