David and Samantha Cameron make their way to Ivan's funeral
David and Samantha Cameron have held a private funeral for their eldest son, six-year-old Ivan, who died last week.
The service, attended by close family and friends, was at St Nicholas Church, Chadlington, Oxfordshire.
Ivan, who suffered from cerebral palsy and severe epilepsy, was described as a "beautiful boy" by his parents.
Tory leader Mr Cameron, who has a daughter and another son, has said he was "overwhelmed" by the letters and flowers sent in condolence.
The Camerons arrived for the service holding hands, with Mrs Cameron wearing a black dress with blue polka dots and a red scarf. She carried a small bunch of flowers.
Mr Cameron wore a dark suit with yellow tie.
He had been an MP for Witney, Oxfordshire, for less than a year when Ivan was born in April 2002.
He suffered from Ohtahara syndrome, a rare form of epilepsy characterised by spasms which start in the first days of life. Some children can suffer as many as 100 seizures every day.
At House of Commons question time, Communities and Local Government Secretary Hazel Blears sent her "very warmest thoughts" to Mr and Mrs Cameron "at this difficult time for them".
This picture of Ivan was released by the Cameron family on Tuesday
Junior communities minister Iain Wright said: "I'm sure the whole House will want to say our thoughts and prayers are with David and Samantha on what must be a particularly unbearable day."
Liberal Democrat communities spokeswoman Julia Goldsworthy also expressed her sympathies.
For the Conservatives, shadow communities secretary Caroline Spelman thanked ministers for their "kind" words and said she would pass them on.
Friends said the experience of caring for Ivan broadened Mr Cameron's political outlook and made him a passionate supporter of the NHS.
"It means a lot to know that others are thinking of us and him," the Tory leader said in an e-mail sent to party members, activists and staff at the weekend.
"He leaves a hole in our life so big that words can't describe it... we all just miss him so desperately."
The Camerons have asked people to send donations to Mencap or the Friends of St Mary's Hospital rather than send flowers.