In the 24 hours to 9am on Sunday, a total of 164,849 tests were provided and the testing capacity for the day stood at 294,258.
The change came as DHSC data revealed that, since testing started, a total of 10.5 million tests have been “made available” but only eight million have been “processed”. That means that as much as a fifth of tests – more than two million – are either not being sent back to laboratories or are being voided.
Number 10 accepted that some people were opting not to carry out the process of sending their test back for examination after receiving their home coronavirus testing kit.
The spokesman added: “It will be the case that some members of the public may order a test and then, for whatever reason, they choose not to return that test. Obviously, if people are ordering tests it is entirely right that we should provide them with one.”
The spokesman said he had not seen a “verified number on this” when the figures were put to him.
Baroness Harding, who chairs NHS Improvement, said people who have been identified as having come into close contact with confirmed virus carriers might test negative despite going on to develop symptoms.
Citing advice from the chief medical officer, she said a misleading negative test result risked encouraging close contacts to venture out into the community rather than staying at home for 14 days.
“You could easily start to become infectious on day four, five, six, seven, etc,” she said.
Public Health England is currently undertaking a study to establish the likelihood of testing negative on any given day and going on to develop symptoms. Clear results could enable officials to shorten the time for which people are required to self-isolate.
Labour accused the Government of using the policy change to hide that it had failed to hit its testing target, arguing that ministers could not show that 100,000 were ever being tested on a daily basis. The shadow health minister, Justin Madders, said: “This is an absolute shambles.”