A 12-year-old boy and his parents were invited to meet the prime minister's wife, Samantha Cameron, at 10 Downing Street after the total they raised for charity smashed through the £50,000 barrier.

The Rowlands family – Paul, Miranda and their son Sam, from Spixworth, near Norwich, started raising money for Ronald McDonald House Charities after the death of baby Alice in 2007.

RMHC provides accommodation for families whose loved ones are in hospital miles from home, and the family stayed for two weeks at a Ronald McDonald House in London to be near Alice, who was receiving treatment for acute liver failure at nearby King's College Hospital.

Alice died when she was just 15 days old, but the family pledged to raise money for the charity in her name and set up the Alice Rowlands Memorial Society.

The total raised has now exceeded £50,000 and the family was invited to a charity reception last week to celebrate the charity's work.

Sam, who goes to Sprowston High School, said: 'It was great we were all able to stay together at the Ronald McDonald House. It meant we could visit Alice whenever we wanted to and when Alice was 10 days old I was allowed to hold her, which was very special.'

As part of the fundraising campaign, Sam has sold some of his cherished toys, written to celebrities to request items for auction and helped organise gala dinners. He said it was amazing to meet Mrs Cameron. 'I told her about what we do and about the things we have been doing and what we have organised, like the gala dinner and selling some of my toys.'

Mrs Rowlands added: 'We work as a fundraising team and call ourselves, Team Rowlands. When Sam's dad, Paul carried the Olympic Torch last year, he took the torch into his school, to raise awareness of the charity.'