An NHS watchdog has severely reprimanded a private company providing out of hours GP services in Cornwall which was short of staff, provided inadequate training, left patients facing long waits and manipulated its results.

Serco, which had a turnover of £4.6 billion in 2011 and is poised to win new contracts from the NHS under the changes introduced by the Health and Social Care Bill, made some doctors work double 13 hour shifts overnight and other staff work 11 hour daytime shifts.

The finding is a serious blow to the Coalition government’s drive to introduce more private sector provision into the NHS, to stimulate competition and drive up standards.

One patient complained of having to wait at a clinic for 90 minutes. Another waited so long for a home visit they gave up and dialled 999.

Serco acknowledged that it had underestimated demand over the Easter weekend, and that it was unable to cover some GP shifts over the May Bank Holiday, meaning that people received a slower service. The company has been given 14 days to explain how it will correct the failings exposed in the report by the Care Quality Commission (CQC).

Ian Biggs, deputy director of CQC in the South said:

“At least half a million people depend on this service, so it is vital that it is properly staffed with properly qualified GPs who are available when people need them.

“At times, Serco has not had enough doctors on duty and it is hardly surprising that people have complained. Asking GPs and their drivers to work such long hours should be a last resort.”

Under the NHS bill, primary care trusts are due to divest themselves of services they provide by putting them out to tender, creating a potential bonanza for the private sector. The remaining bodies will be replaced by clinical commissioning groups responsible for purchasing services.

But the failings identified in Cornwall, where Serco provides out of hours GP services to a population of half a million, are a damaging setback for the policy and suggest private companies may not be up to the job.

The CQC investigation was triggered by whistleblowers who alleged that patient safety was being threatened by the shortage of staff, inadequate record keeping and a bullying culture.

Inspectors made unannounced visits to the company’s call centre in Truro and five clinics during April and May. They found Serco was in breach of four of the eight essential standards, including failing to protect vulnerable adults and children from abuse.

Inspectors found the company had been manipulating its daily performance reports by altering incorrect entries which showed the service was failing to hit its targets. But it did not carry out similar checks on the accuracy of entries showing it had hit its targets – and inspectors found two examples of failed calls which had been wrongly classified as achieved.

The report said there was no evidence that the figures had been deliberately altered to enhance performance but problems with the computer system had been known about for years and had not been resolved.

Although the company had a whistleblowing policy in place, some staff said they were worried about repercussions if they spoke out.

Mr Biggs said “We haven’t found that the company have been deliberately misleading the people of Cornwall about their performance, although quite clearly the system of monitoring performance is unreliable.

“When the managers correct the data, only the calls that would improve the overall daily performance are subject to checking and reclassification, so that must raise questions about the accuracy of the data. It is possible that the performance of the provider may be overstated in their reports.”

Serco had recruited more GPs and introduced a new system to cope more effectively with calls, the report said .

Paul Forden, Managing Director of Serco’s Clinical Services, said action had been taken to ensure the required standards were met.