Cowell invites cancer boy Kian, 5, to his son Eric’s 4th birthday bash

30, of Prudhoe, Northumberland said: “I got a message from Eric’s mammy asking if we’d like to go to his party.

“Simon paid for us to be chauffeur driven and our train journey, he’s so kind. We have arrived at this real luxurious hotel in a Jaguar. Kian is loving it.”

Having a great time with Eric, little Kian played on a bouncy castle then leapt into what he thought was a ball pit – but turned out to be a pool of water. But his soaking proved no problem with such generous hosts.

Kat said: “Kian had to be taken away by Eric’s nanny. They dried him off and ordered some more clothes for him. It was very good of them to do that.”

She added: “It has been a fantastic day and we thank Simon so much.”

In December, Kian and his family were invited to watch the X Factor final in London and the cheeky youngster was caught on video dancing in front of thousands of people on the stage.

Kian was 18 months old when diagnosed with the aggressive cancer. Wellwishers donated over £600,000 to send him for stem cell treatment in New York.

He has recently returned from his final round of treatment in the US, and hospital tests over the next year will show whether it was successful.

Kian suffers from the same rare disease as tragic Bradley Lowery, of Blackhall, Co Durham, who died of neuroblastoma aged six in July last year.