Each person arriving in to the UK must continue to complete a Passenger Locator Form before arrival. Asking about 20 questions, including cabin flown, the form takes a little while to complete. Whilst I have only ever been asked for it once, we are told that it is linked to the automatic passport reading eGates. No PLF, No eGates. I am not sure if that’s true!
Anyway, the UK Government has suggested that the form may be going away by the Easter holidays. In the meantime that have extended the period in advance of ARRIVAL that you can complete it to three days.
Not a big concession, but if you have a long flight or series of flight to get to the UK, it should reduce the stress of filling in the form.