Mum Harriet Cox will be joined by a 50-strong team of cyclists to tackle a 100km bike ride in memory of her five-year-old son, Bobby, who died of a brain tumour seven months ago.

The 41-year-old, of Bath Road, Marlborough, has organised Bobby’s Ride to raise money for the John Radcliffe Hospital in Oxford, where Bobby was treated, and The Brain Tumour Charity.

Bobby, a pupil at Preshute Primary School, was diagnosed with medulloblastoma, a brain tumour that mainly affects children, on Father’s Day last year.

Doctors said he would live for another five years but the tumour was very aggressive and spread to his spinal cord and other areas of his brain. He died two and a half weeks later on July 2.

Mrs Cox, a house mistress and biology teacher at Marlborough College, said: “He had a really good sense of humour and he loved living in the house with all the girls and having loads of big sisters.

“He loved his football, Lego and Star Wars. He just wanted to run around and play all the time and he was so good when he was ill.”

The ride will set out from Marlborough College at about 8am on Sunday, May 24 and the cyclists will be able to stop off en route at Pinewood School, Bourton.

Mrs Cox’s 51-year-old husband, Paul, a theatre manager, will be on hand on the day to offer technical support to anyone who encounters problems along the route.

Mrs Cox, who has an eight-year-old daughter called Phoebe, is hoping to raise £30,000 which will be split evenly between the two causes.

She said: “We went back to the hospital in September and we were thinking about things we could do and organising this ride felt like a fitting way to recover from the shock of losing Bobby.

“We made the journey to Oxford so many times that it seemed the right place to cycle to and 100km seemed like a nice round number.

“We’ve raised quite a lot for the hospital. After his funeral I set up a Justgiving page which has had about £8,000 in donations.

“We wanted some of the money raised to go towards research because not a lot of money is spent on it even though brain tumours are the biggest cancer killer of children and adults under 40.”

As well as the cycle to Oxford, some of the Marlborough College students living in Elmhurst, where Mrs Cox is house mistress, are planning a 24-hour ride on static bikes to help raise funds.

To sponsor the ride visit uk.

virginmoneygiving.com/bobbycox