Those who believe that Rebecca Tomlinson will enter the London Marathon today in honour of her mum are missing the point, and missing the essence of what makes her a true Tomlinson.

Rebecca is a university student, running for her own sense of achievement among the 40,000 who come from around the world to take part. And, yes, her chosen charity, Jane’s Appeal, bears her mother’s name and will most likely shoot through the £2m mark this morning.

For her mum’s cause, maybe. But not in her mother’s stead.

“Dad knows that I’m very stubborn and I don’t get pushed into anything for my mum’s sake or anybody else,” she says. “That’s just wrong. Obviously I want to help with the charity, but I don’t feel the need to run for mum. Twenty-six miles is a lot of effort if you’re not going to enjoy it. Truth is, I’ve always wanted to do the marathon.”

Rebecca, if you haven’t already guessed, is the daughter of Jane Tomlinson, the Yorkshire woman who died last September after responding to the prognosis that she had months to live with incurable cancer by stretching out her life for a further seven years in which she ran, swam and cycled astonishing distances to raise money for cancer research and children’s charities.

The wonder of Jane was that she was not at all athletically trained, and did nothing in that line until she was told her time was running out. She resolved to test her breaking body beyond limits she never knew she had. Her daughter Rebecca, on the other hand, was the family’s athlete, a competitive runner from primary school onwards.

So it started. Jane was led on her formative jogs by Rebecca, the middle child of three. Rebecca was 14 then and is 20 now, working for a degree in media and American studies at York St John University. Along with her father Mike, older sister Suzanne and younger brother Steven, she saw the world while supporting their mother’s feats in running marathons, completing the ultimate endurance event, the Iron Man triathlon in Florida, and cycling 4,000 miles across America despite undergoing chemotherapy.

The children grew into young adults while they watched the transformation of their mother into somebody quite extraordinary. Before just one of her London marathons, in which 45 Sunday Times readers volunteered to run for Jane’s fund, I had been summoned to the family home in Rothwell, near Leeds.

If the newspaper was to be a part of her endeavour, and to support it going forward, the deal was that we should present our idea to the family as a whole. It was Rebecca who, at that kitchen table, cut to the chase and announced that it was “cool” to let the world know what feats their mum would run, and what the Tomlinsons were willing to share with the public.

These were exceptional children, made to grow up prematurely by the knowledge that one of their parents had precious little time in which to fulfil ambitions that appeared to multiply rather than recede under notice of death.

There was so much fun in that home, so much courage, so much resolve to face the fact and do something outstanding while time permitted. Jane was the driving force, Mike the organiser, the children and their grandparents and aunts and uncles all turning a horrifying sentence into a series of triumphs.

Fast forward to today. Mike Tomlinson and his daughter will run the marathon for the same appeal, but as separate races. “It’s pretty weird, pretty cool the letters that keep coming through the door,” says Rebecca. “Dad’s never stopped working on the appeal but almost every day that I’m at home there are cheques in the post, and letters sent personally to me as well with words of encouragement.”

She doesn’t have a doubt or a fear about the distance. At 5ft and weighing little over 7st, Rebecca is even smaller than her mum, with a build similar to Gete Wami, the Ethiopian who is favourite to win the women’s event. Wami says that the unexpected happens in every marathon, no matter how well prepared you are. But Rebecca has put in the miles, sometimes accompanied on a bicycle by her student housemates on the outskirts of York, “until they get bored and leave me to it”.

“It’s just something I’ve always liked,” she says. “It started with the 50 club at primary school, when we used to run during the lunch break to see if we could get to 50 miles in total during summer term. When I’m out running, even if I’m stressed, I think of nothing. I’m just concentrated on my running, and I’m pretty competitive. I like being with myself, and sometimes feel the need to run faster.”

She makes running sound like a freedom, a privilege the way Sir Roger Bannister once described “floating on air” when as a boy of nine he ran on a beach. “I’ve got lost, literally, running,” Rebecca said. “I went to see my Gran and went out for a three-mile run in the Dales. I felt so good, I just kept running, I don’t even know where, but it was probably another six miles.”

She has no set plan for the London Marathon, other than to finish in around four hours. “It’s not really fast but I’m more interested in completing the course,” she says. She foresees herself running alone among the mass field. “I don’t think I could run far with dad,” she reflects. “The furthest we’ve run together is about four miles, and I don’t think he loves running as much as I do.

“He does it because he wants to beat mum’s time of around 4hr 58min [4hr 53min according to dad]. He’s out there to keep up awareness of the charity and keep mum’s events going.”

Mike Tomlinson’s start number 32,827 puts him ahead of his daughter’s 32,828. She doesn’t imagine it ending that way. Rebecca will not be thinking in terms of legacy. Her dad will. “The other day,” he said, “Becky said she just wants to experience the event. That’s fine, but for a lot of people Jane’s said it’s okay to be active even if you have terminal cancer. We’ve a long way to go with that yet.”

A long way, despite the fund standing at £1,950,000, with two million almost a stride away. After that there will be a new target in Jane’s Appeal. As for Rebecca, a triathlon is on her horizon, not, you understand, because of mum.

Visit www.janesappeal.com or send your donation to Yorkshire BS, 46-48 Commercial St, Rothwell, Leeds LS26 OAW More than 100 marathon runners have signed up to raise money for Help for Heroes (H4H), a charity whose aim is to raise at least £6m to help build a swimming pool and gym complex at Headley Court, the tri-service rehabilitation centre in Surrey. For more information on H4H, go to www.helpforheroes.org.uk