Two teenage cyclists crossed the border today as part of a marathon ride the length of Britain to raise money for charity.

Instead of sitting around doing nothing during school holidays, 15-year-old Tom Claxton and 16-year-old Giles Calder got on their bikes.

The pair set off from John O’Groats last Wednesday and hope to arrive at Land’s End 1000 miles later.

The teenagers, who attend Lomond School in Helensburgh, want to raise cash for international charity WaterAid.

Tom said they decided to do the challenge after being inspired by what the charity WaterAid does for communities in developing countries.

WaterAid is an international organisation that aims to transform lives by improving access to safe water, hygiene and sanitation in the world’s poorest communities.

He said: “The charity makes such a big difference to people’s lives that we just thought we wanted to do something to raise money for it. Cycling is a big hobby of mine and Giles so this challenge was a good idea.”

Tom revealed that his mum finally accepted the idea after being a bit apprehensive at the teenagers’ trip. He said: “My mum was a bit unsure at first but now we’ve got everything sorted she’s fine.

“We will have a support car with our relatives in it for the whole trip so we won’t be completely alone but it will just be me and Giles cycling.” Tom said they decided to undertake the challenge last Christmas and have been trying to get in cycling practice since then.

He said: “We’ve never done anything like this before.

“When we told friends at school most were really supportive but some were doubtful that we would make it – but we definitely will.

“Once we get going and into the rhythm of cycling, any nerves will fall away and we’ll just get on with it.” Celebrities including the comedian David Walliams and presenters Fearne Cotton and Davina McCall cycled from John O’ Groats to Land’s End earlier this year and raised more than £1 million for Sport Relief.

Tom and Giles have raised £1100 for their cause so far by giving a presentation at school to their peers on how WaterAid can help people.

The friends also set up a charity internet page – www.justgiving.com/Britain-On-A-Bike – so people can sponsor them online.