The list itself was revealed just a few hours before the scheme came into force on Tuesday (15 December) – the best part of two months after it was initially detailed by transport secretary Grant Shapps in mid-October, and a month after it was formally announced in mid-November.

However, shortly after the list of just 11 providers was published by the Department of Health on Monday, this was effectively cut to 10 when Samedaydoctor asked to be removed.

In a note posted on its website, the provider said: "Unfortunately, we have been so overwhelmed with requests for test and release that we cannot answer any more emails nor take any more bookings and we have asked to be removed form the government list."

According to The Times, two other providers – Medicspot and Screen4 – reported testing backlogs that would initially hamper their test to release capacity.

Test to release will allow people returning from non-travel corridor destinations to take a test on the fifth full day day of their mandatory 10-day self-isolation requirement which, if negative, will allow them to exit quarantine early.

It still remains unclear which testing standards are acceptable under the scheme, with all 11 providers offering various different Covid tests.

The list states: "There are different requirements for this scheme, which means that some providers for the general testing may not meet the minimum standards for test to release for international travel."

General testing providers, many of which also feature in the list of certified test to release partners, are listed on the same page.