Sam Waley-Cohen will fulfil a childhood dream when he rides the tough mare Liberthine in the John Smith's Grand National tomorrow, writes Russell Smith.

The amateur jockey, from Edge Hill, near Banbury, who is 25 the day after the big race, can't wait to tackle Aintree's formidable fences in the world's most famous steeplechase.

"It's what I dreamed of as a schoolboy," he said. "I never thought I'd like to walk out at Twickenham or Wimbledon, for me it was always the Grand National."

A commodities trader, who spends much of his time travelling between Paris and Geneva, the former Edinburgh University politics student is looking forward to chancing his arm in the most physically-demanding test in horseracing.

"I've been lucky and done a lot of extreme sports like white-water rafting, mountain-climbing and skydiving," said Waley-Cohen.

"I also own a pilot's licence, but frankly, they are like kindergarten compared to the National fences.

"It's probably as close as you can come to flying without sprouting a set of wings."

But Waley-Cohen has ridden a lot of good racehorses for his wealthy father Robert, a director of Cheltenham, an Aintree steward and a Jockey Club member.

Horse and rider already have formidable Aintree credentials, with the Nicky Henderson-trained Liberthine - recently covered by Hernando - showing admirable fighting traits over the daunting spruce fences last April to win the Topham Chase.

It was the culmination of a remarkable 24 hours for Waley-Cohen, who on the Thursday of the Aintree meeting completed back-to-back Fox Hunters' victories over the big obstacles aboard "family pet" Katarino.

"Without a good horse, a jockey is nothing at Aintree," insisted Waley-Cohen.

"But then again, it is partly the atmosphere of the place as well. I think that probably brings out the best in Liberthine and Katarino, and I think it probably brings out the best in me."

The Waley-Cohens also enjoyed success with Liberthine in the Mildmay of Flete Chase at the 2005 Cheltenham Festival - a poignant success as nine months earlier, Sam's younger brother, Thomas, lost his long fight with a rare form of bone cancer and died at the age of 19.

"Everything was still raw after what happened to Thomas and it was such an emotional day," said Sam, who still rides with Thomas's initials stitched into his saddlecloth.

"Losing Thomas was terribly hard for all of us and he loved his racing.

"These big meetings are always big family occasions for us and it brings home the fact that's he's not there."

Since Thomas's death, tireless charity work has yielded an incredible sum of nearly £1.5m, which has helped raise money for the Oxford Children's Hospital.

The family gleaned enough funds to see the January opening of a 24-bed general surgical ward, named in Thomas's memory.

"People often ask if I want to win the National for Thomas, but in truth, I want to win it for him as much as I do for the rest of my family, who all mean so much to me," said Sam.

And what of the quietly-fancied 25-1 chance Liberthine?

"I think the National is a test of character, and the horse with the biggest heart and desire often wins," Sam concluded.

"What a horse needs when jumping over the National fences is courage and guts. And Liberthine has stacks of that."