Conservative Party leader David Cameron and his wife Samantha have passed on their thanks for the messages of support after the death of son Ivan, their "beautiful boy".
Six-year-old Ivan, who had cerebral palsy and epilepsy, died at St Mary's Hospital in Paddington, London.
William Hague, standing in for Mr Cameron as question time was suspended in parliament on Wednesday, said Ivan had brought "joy and love to those around him".
Prime Minister Gordon Brown said everyone's thoughts and prayers were with the family.
Mr Brown, who suggested suspending the weekly Commons clash as a mark of respect, said every child was "precious and irreplaceable" and that the death of a child "was something that no parent should have to bear".
The prime minister, whose daughter Jennifer Jane died aged just 10 days in 2002, paid tribute to Ivan saying: "I know that in an all too brief life, he brought joy to all those around him and I know also that for all the days of his life, he was surrounded by his family's love."
Mr Hague told MPs he had spoken to Mr Cameron, who wanted to pass on the family's thanks for their messages of condolence and say how "hugely grateful" they were to the NHS staff who had helped Ivan throughout his life.
Mr Hague said: "Ivan's six years of life were not easy ones. His parents lived with the knowledge for a long time that he could die young, but this has made their loss no less heart-breaking.
"Ivan suffered much in his short life, but he brought joy and love to those around him and, as David himself has said in the past, for him and Samantha he will always be their beautiful boy."
MPs from across the political spectrum have expressed their condolences to Mr Cameron, who has been leader of the Britain's official opposition since 2005.
Buckingham Palace said the Queen had sent a private message of sympathy.