The problem is an escalation of long-term shortages of GPs as more medical students decide against working in general practice, combined with stricter rules on who can work as a locum. Since January, only those trained for general practice have been able to act as locums, which rules out other doctors, such as retired surgeons.
Dr Lawrence Singer, chairman of the Association of Small Practices in Essex, said the problem was particularly bad in rural areas. "We have a number of members who haven't had a holiday for four or five years," he said. "The problem is getting progressively worse. My day is from 7am to 10pm and you can't get people to stand in for that."
Jackie Maun, chairman of the Association of Managers in General Practice, said staff could spend hours on the telephone leaving messages only to find two days later they were still without a locum. "Two or three years ago if you said, 'we've got to find a locum', it didn't elicit the groan that it does now."
Dr Bob Button, secretary of the Hampshire local medical committee, said there were problems. "But going away can be the least of it. It's when a GP suddenly drops down ill that it's much more troublesome."
When one GP had to go into hospital recently, the health authority could find no locum and another practice had to take over the patients. "It is a problem the Government has been ignoring for a long time," he said.
Frances Cloyne, the Wessex faculty manager for the Royal College of General Practitioners, said: "Obviously there is a need out there. I know from experience that GPs are having difficulties, particularly for the summer holidays."
Jayne Mills, who runs the Taunton GP Locum Agency in Somerset, said the situation was "reasonably serious with the potential to get a lot worse". She went on: "All the locums are booked to the hilt to September. Until last night I had 60 sessions that I didn't think I was going to be able to fill, but someone has come back from abroad for three months and is helping out.
"There are always pressures because of holidays, but the feedback this year is 'we're not going to get away this year'."
Research carried out by Professor Ray Robinson at Southampton University showed that trying to find a locum was one of the greatest pressures on a single-handed practice.