A nine-year-old boy with an inoperable brain tumour is climbing 52 metres into the London skyline in aid of a charity that gave him a trip to remember.

Malachi Tyler, also known as Kingston’s youngest police constable, and his dad Graham are scaling the O2 to raise money for Post Pals, which sends cards and letters to seriously ill children and organises small wishes, parties and treats.

His tumour and neurofibrosis were diagnosed when he was just 15 months old, and he went completely blind at 18 months.

In 2014 he had a day at Kingston police station where he handcuffed and used training pepper spray on an officer, and he took part in a passing-out ceremony in full uniform in 2015.

More: Kingston police help six-year-old cancer patient tick off 'bucket list'​

More: Malachi Tyler, Kingston's youngest PC, completes passing-out ceremony in full uniform​

Post Pals charity sent him and his family to Chessington World of Adventures for a weekend away last year, and he hopes to raise enough to send another family away for a break from hospital life.

Malachi said, “I am so excited about climbing the O2 to help poorly children like me.”

Post Pals is run by volunteers, so all the money will go to helping the children.

Malachi also sends and receives cheerful post through the charity, to keep him and other children like him in good spirits.

Graham, Malachi's dad, said: “This is an important challenge for me to have taken on as I to myself have just been given the all clear after 10 years of Cancer. Knowing every penny of the money I raise will be used to provide a break for families to create precious memories together makes it worthwhile.

“Post Pals took 60 families there in 2016 and made it accessible for even the sickest of children. Sadly, since the trip some of the children have since passed away and I would like for other families with a seriously ill child to be able to have happy hospital-free memories.”

The climb will take place on October 7. To donate, visit justgiving.com/fundraising/graham-tyler63.