Official figures reveal that ten million patients are struggling to see their GP because surgery opening hours are too restrictive.
The worst-rated practice in a nationwide patient survey does not open until 10am, shuts again for a three-and-a-half-hour lunch and closes one afternoon a week.
GP surgeries are causing increasing resentment among the public, who are finding it ever more difficult to secure an appointment.
Family doctors last night said they are overwhelmed by growing demand, and increasingly unable to provide safe levels of service. But some of the least popular GP practices were found to be closing for up to three and a half hours at lunchtime, as well as closing their doors for full afternoons and weekends.
Katherine Murphy, chief executive of the Patients Association, said: "We know many surgeries are struggling to cope with demand due to a lack of funding, and a shortage of staff. There must be further investment."
Maureen Baker, Chairman of the Royal College of GPs, said family doctors were working harder than ever to meet increasing demand from a growing and ageing population, but did not have enough resources to do so.
Many practices are already offering extended opening hours but, for the majority, with current resources, seven-day opening remains an aspiration.
An investigation by the Mail last year revealed how GPs are taking early retirement because it is not profitable to carry on working. The Government has imposed a Ģ1.25million limit to pension pots, and many GPs reach this by their mid-fifties.