Holidaymakers are thought to be spending more than £11 million on PCR tests for travel, at a cost of £75 each on average. 

The tests have been designed to enable the government to detect the import of variants that could "threaten" the vaccine programme - but more than 40% of the results from the 350,000 PCR tests a week on amber list travellers are being recorded as "unregistered". 

The Telegraph, citing "experts", reports that without this data, it would be very difficult for the government to trace individual travellers involved in any outbreak of a new variant that has entered the UK.

Robert Boyle, a former chief strategist for British Airways (BA), reportedly uncovered the data in newly released government figures. 

He told The Telegraph: "Based on what we have seen from the testing data, I think we can add data management as another area where the system is failing dismally and seems to be in a state of disarray.

"For a system whose primary purpose is to provide decision-makers with high quality intelligence on travellers arriving in the UK, that is a big issue.

"The data are being provided by the traveller in most cases but are disappearing into a test-provider black hole, and is never being passed on to Test and Trace."