During the 2003 outbreak of SARs CoV 1 it was at the positive chest x-ray point in the diagnostics procedure that a RT/PCR test was done to ascertain whether it was actual SARs or one of the other half dozen common causes of viral pneumonia.

China is/was using chest xray for SARs2.

Yes we dont have specific symptoms and the UK list is too vague but there are some which dramatically increase the chance of a person having it which is the whole point.
They're far more likely to have it than people with none if they have several of those.

With the low prevalence of SARs CoV 2 and the higher prevalence of other infectious agents combined that can cause smell/taste loss a positive RT/PCR test result with smell/taste lost symptoms still has a high probability of being a Type 2 error. A false positive.

Wheres the data showing a high probability? (We're also not at low prevalence now)
So given that the vast majority of the hundreds of thousands of RT/PCR tests done ever day are not the result of negative antibiotics response / positive chest x-ray clouding you can be mathematically certain that the vast majority of RT/PCR positive test results will be Type II errors. False positives.

Whereas your data and working for this?

Ultimately Pillar 2, if used correctly will produce some false positives but given its used as a secondary diagnosis not the sole they're manageable, especially with higher disease prevalence.

A little more data from NextStrain on sequences.

Turns out the UK Super-covid is genetically different from the Welsh strain and the new today South African.
All have evolved the same mutation separately (meaning it likely has a selective advantage).
Common ancestor of those was pre March 2020.

There is absolutely zero point locking up areas to control the spread - its popping up in different lineages everywhere.

Useful thread on it here:-
https://twitter.com/firefoxx66/status/1341793323535757312