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Mr Campbell began his career working in Michelin-starred kitchens, and came second on the BBC's Young Chef of the Year when he was 20-years-old.
He spent some time working in the French Alps as a private chef for "VIP guests", according to his website.
Mr Campbell went on to work at as a chef at private villas along the Cote D'Azur and luxury ski chalets, as well as run culinary courses in India and Thailand and a pop up restaurants in Belize.
Writing on his website, he said he was looking forward to his plans for this year. "2018 is looking exciting, a UK 'roadshow' announced, filming for a TV pilot, planning my cookbook, collaborating with brands and working towards my first food start up," he wrote.
Mr Campbell was raising money for the Brathay Trust, a charity based in Ambleside, Cumbria which runs training and skills for youth and young adults.
His original target was £2,500 but by Monday evening, he had raised over £50,000 as donations poured in from members of the public moved by his story.
He told how his father Martin, who died 18 months ago, worked "tirelessly" for the charity and through his work, had "helped change many lives for the good".
On his JustGiving page, Mr Campbell wrote: "As many of you know, I lost my father Martin 18 months ago suddenly. The past year and a half have been the toughest of my life but his spirit and energy live on in me.
"Although he won't be there in person, I know he will be there in spirit and I will be running for him."
He went on to describe how his father was "the most inspirational man in my life".
"[He] was the one who said – 'Go on, why don't you give it a go? I know you can do it!' and entered me into my first marathon; Brathay 2016 along with my brother, Josh," Mr Campbell wrote on his fundraising page.
"It was maybe the proudest day of my life standing at the finish line having achieved something I never imagined possible with my Dad & my Brother by my side."
A spokesman for Virgin Money, the race organisers, said: "With deep sadness, we confirm the death of a participant in the 2018 Virgin Money London Marathon.
"Matt was a well-known chef who featured in Masterchef: The Professionals last year, inspiring viewers with his Nutritional Gastronomy movement and forward-thinking ideas. He was running for The Brathay Trust and in memory of his father, Martin, who died in the summer of 2016.
"Matt's family today paid tribute to their inspirational son and brother. Matt's chosen charity, The Brathay Trust, inspires vulnerable young people to make positive changes in their lives.
"Everyone involved in the organisation of the London Marathon would like to express our sincere condolences to Matt's family and friends."
The spokesman said that the exact cause of death will be established by later medical examination.
MasterChef paid tribute to Mr Campbell, praising him for "some of the most innovative and groundbreaking food that we saw on the show".
A spokeswoman for MasterChef said: "We are shocked and saddened to hear the news about Matt Campbell, one of our talented contestants from last year. It was a privilege to have him on the show."
"From the whole MasterChef team, our sincere condolences and thoughts are with his family and friends."
The Brathay Trust said they are "devastated" by the death of Mr Campbell. "Matt and his family have been tireless in supporting the work of Brathay Trust and our thoughts and prayers are with them at this terrible time," a spokesman said.
"Matt became involved with Brathay Trust through his father Martin, who was a key member of the team delivering the Brathay 10in10 (10 marathons in 10 days) until his untimely death in the summer of 2016."
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