-in June, there were reports of waits up to six hours at Heathrow arrivals to be processed.
--not having to show vaccine information at immigration will make it faster. There is no standard form for vaccines so it would take time for the agents to figure each one.
Those headline grabbing long waits were not typical. It was a perfect storm of insufficient border agents (distancing measures meant that every other desk could not be manned because screens had not been placed between between posts. Instead of getting on and installing them both the Border Force and Heathrow Airport kept passing the buck over who was responsible for financing the screens. This has now been rectified after intervention from the Home Secretary and now the desks are all fully staffed). Along with the arrival of extra flights laid on by the airlines to cope with the increased demand from passengers desperate to return home before the country they were in was placed on the red or amber list.
I've been through Heathrow since and I can assure you, my experience was nothing like those news reports. There's also no standard documentation for proof of a negative test. It all depends on who conducted the test and how they produce the results. Some passengers had the information in electronic form on their phones or tablets, others had it printed out on paper, all of which had to be checked by an agent along with a passport check and the passenger locator form both of which will still need to be done in the fast track line however this doesn't take long at all, all of 30 seconds in my case.