Members of a family from a Harborough district village, including a ten-year-old girl, completed the Yorkshire Three Peaks Challenge earlier this month.
Youngster Grace Hartley, her sister Olivia (14) and mum Nicky, from Church Langton, reached the summit of Pen-y-ghent before then conquering Whernside and then Ingleborough.
It is thought Grace is the youngest person yet to complete the trek.
They completed the feat on Saturday, August 9, having started at 7.15am and finishing in 11 hours and eight minutes, well under their target of 12 hours.
Grace, a pupil at Church Langton Primary School, was taking on the challenge to raise money for The Harley Staples Cancer Trust.
She has so far raised £965.
Proud mum Nicky said: “It was really tough going as the weather was so hot.”
People can still donate to the cause, via the website https://mydonate.bt.com/fundraisers/gracetheacehartley.