He’s known as TV’s Mr Nasty, but Simon Cowell has left one family in shock with his generosity.

Toddler Kian Musgrove was diagnosed with stage four cancer for the second time in 2014 – and his mum Kat has desperately trying to raise the money to send him to the US for treatment.

Seeing Kat’s plea on Twitter, Simon – who is dad to two-year-old son Eric – got in touch to donate £25,000 to the cause.

The 56-year-old also encouraged his followers to help, writing: “Kian Musgrove is a truly brave young boy. I have just spoken to his mum. Let’s help him get to NYC for the life-saving treatment he needs #CaringForKian #GetKianToSimon [sic].”

Discussing X Factor judge Simon’s kindness, Kat told the Mirror: “I can’t believe it, I have tears streaming down my face. He just called up and said he wanted to drop £25,000 into our fundraising account.

“I’m still trying to get my head around it all. He was so nice and kind and just said he wanted to do something to help.”

Kian, now three, was initially diagnosed with neuroblastoma in October 2013. The little boy endured months of chemotherapy to make the cancer undetectable, before the family were rocked by the news he’d relapsed over Christmas last year.

A message posted to Facebook read: “Kian is a 3 year old boy from Newcastle who has spent half of his life in and out of hospital fighting neuroblastoma. He relapsed at Christmas and there is only so much that can be done here in the UK with just a month left of treatment.

“At the moment Kian is very poorly. He has raging temperatures, rigours, sickness and diarrhoea whilst he goes through intense chemotherapy again. We currently have £285k for Kian but we need £500k to get him treatment in New York. How can you put a price on life? [sic].”

If you would like to donate to Kian’s cause, click here.