The Prime Minister has been accused by Riven Vincent of breaking an election pledge to ensure more is done to support families in her situation.
Her daughter, six-year-old Celyn, has severe quadriplegic cerebral palsy and epilepsy and requires round-the-clock care, but her parents receive just six hours respite a week.
Cameron has denied that the coalition's austerity measures are preventing the family from getting more help, stating he will look ‘very closely’ at her case.
BPPA chairman Bingle said: ‘The PM should have resisted the temptation to get personally involved. It sets a very dangerous precedent.
‘It is inevitable that there are going to be lots of very sad personal stories in the months ahead. Is the PM going to involve himself with every one of them? Of course not.’
The media are inevitably drawing parallels with Cameron's eldest son Ivan, who had severe disabilities and died in 2009 at the age of six.
Bespoke Speeches founder Simon Lancaster agreed that Cameron was visibly upset by the story: ‘his voice was cracking, eyes blinking, cheeks flushing’.
‘But as the cuts kick in, there'll be thousand more desperately sad stories like that of the Vincents and Cameron can't personally look into every one, no matter how tragic they are,’ he added.
‘He needs to show how the Big Society he wants will look after families like the Vincents, translating his national vision into personal realities. If he fails to do that, people will see it all as a big puff of smoke.'
Freelance public affairs consultant Lionel Zetter added that it is 'clearly a difficult situation for Cameron', as he has had to balance his personal feelings, unavoidable budget cuts and the coalition's localism agenda - 'and the powerful Mumsnet community'.
‘Cameron the father was clearly in conflict with Cameron the Prime Minister in his response. There will be many more similar dilemmas for him to face in the years ahead.’