Currently, the UK government says (in https://www.gov.uk/guidance/coronavirus-covid-19-testing-for-people-travelling-to-england):
Type of test
The test must meet performance standards of ≥97% specificity, ≥80% sensitivity at viral loads above 100,000 copies/ml.
This could include tests such as:
a PCR test
a LAMP test
an antigen test, such as an LFD (lateral flow device) test
You must check with your test provider that the test meets the standards. You may not be able to travel if it does not.
Travel from Spain and its islands - if you are travelling to England from Spain, including the Canary Islands and the Balearic Islands (Formentera, Ibiza, Mallorca, Menorca), you are advised to take a PCR type test before travel.
Does anyone know how to interpret "advised" (my emphasis) in this context?
My local tourist office says that they have been told that several British people have travelled from my area of Spain to England (and back) with a negative LFD test result.
A local test provider says that their LFD test is suitable for travel to England.
However, I suppose you could say that this is anecdotal evidence.
Does anyone have anything more definitive?