Test and Trace has been “a success”, its former boss has claimed, as she suggested the media was to blame for the public expecting the system to have stopped the second wave.

Baroness Dido Harding said she was “proud” of her contribution to the highly criticised organisation, arguing it had had a “material impact” on infections.

An ally of Matt Hancock, the former health secretary, her comments prompted derision from MPs on the Public Accounts Committee (PAC), who accused her of spending “eye-watering amounts of money” with little effect on the course of the pandemic.

It comes as the latest official data suggested that the Test and Trace system is struggling to meaningfully alter the course of the third wave.

Figures showed one in eight people transferred to the Test and Trace system having tested positive for Covid were not reached in the latest week, the highest proportion since the end of 2020.

Challenged on why the £13.5 billion system had failed to avoid the need for lockdown last winter, Baroness Harding, who formally stepped down in May, said Test and Trace had only ever been intended as one of several weapons in the armoury against Covid, another being lockdowns themselves.

She cited a recent report by the National Audit Office which estimated that the system had reduced the infection rate by between 18 and 33 per cent.

“I would actually argue – and I do appreciate that a lot of people listening to this might find this rather incredulous given some of the way it’s being reported – but I would actually argue that NHS Test and Trace has been a success, that it has delivered on its objectives to help break the chains of transmission, as set out in the NAO report,” said Baroness Harding.

She added: “Test and Trace has always been one of four main planks of our Covid response, not the single one.”

She said the others were non-pharmaceutical interventions in the form of lockdowns and social distancing, vaccines and better medicines for people with severe disease.

However, Greg Clark, who chairs the science and technology committee, pointed out that the Department of Health’s formal business case, presented to the Treasury last year to pitch for the unprecedented funding, had stated that NHS Test and Trace aimed to avoid the need for a second national lockdown.

Mr Clark said: “Procedure is important here. This was in the business case that requested an eye-watering sum of public money, and it was justified on the basis – I’m quoting from the NAO report – that it aims to avoid the need for a second national lockdown.

“That was an important contributor to getting the money.”

Baroness Harding responded: “That’s not the essence of anything I have ever said.”

As the chairman of NHS Improvement since 2017, the Conservative peer had reportedly applied to take over the operational running of the health service as chief executive of NHS England, following the departure of Sir Simon Stevens.

However, Sajid Javid, the Health Secretary, has reportedly ruled out the appointment.

The PAC also heard that the average day rate for external consultants to NHS Test and Trace is £1,100.

Shona Dunn, the second permanent secretary at the Department of Health and Social Care, said there were “undoubtedly” consultants paid more than this, but declined to give details.

Responding to the latest figures from NHS Test and Trace, the deputy chief executive of NHS Providers, Saffron Cordery said: “It is concerning to see another rise in the number of people testing positive for Covid-19, with today’s figures showing an increase of 71 per cent compared to the previous week.

“Despite a slight improvement in the number of positive cases being transferred into the system, it is worrying that 13,623 people were not reached by Test and Trace. This week also saw a drop in performance for test turnaround times within 24 hours.

“As we heard at today’s Public Accounts Committee session, Test and Trace is one of many tools in our battle to break the chains of Covid-19 transmission. But the fact remains that we really need Test and Trace’s performance to improve as Covid-19 infections continue to climb. This is even more important as we approach the lifting of all Covid-19 restrictions on July 19.”