Under the Government's Patient's Charter the ambulance should have arrived within 14 minutes.
The incident occurred last summer to Baroness Cumberlege, Under-Secretary of State for Health, who yesterday described it at the Royal College of Nursing's annual congress in Bournemouth.
She said the health service had to be compassionate and caring as well as efficient and prompt. 'Waiting 20 minutes for an ambulance to arrive with a bleeding, unconscious relative lying on a busy street pavement - my experience last summer - is not caring,' she told nurses at the congress.
At a press conference later the minister said her aunt had survived the incident, but she refused to say in which health authority area it occurred.
She had, however, formally complained. 'They have obviously investigated and taken action, but there is nothing else they can do afterwards except say sorry.' The minister argued that it showed the need for the Patient's Charter standards.
She faced derisive laughter from her audience when she said the new version of the Patient's Charter would include giving appointments for visits by community nurses.
The aim is to give patients a two-hour time band within which the nurse will arrive rather than leave them staying in all day waiting for the nurse to come. As nurses protested they were far too stretched to provide such guarantees, Baroness Cumberlege said the reaction had been 'disappointing'. But she conceded that 'it may mean more resources if we are going to introduce the charter'.
Baroness Cumberlege announced that the first experiments in nurse prescribing were finally to start later this year - leading to predictions that nurses would be prescribing a wide range of drugs within five years.
From October nurses attached to eight GP practices in England will be able to vary the dose of pain-killing drugs that family doctors have prescribed and will be able to prescribe a range of dressings, lotions, ointments and other items in their own right.