Heathrow said passenger and public health would be prioritised over passenger experience, with those due to travel advised to wrap up warm in the event they are held outside to ease congestion.

Coverings are being erected for managed waiting areas outside terminals, with additional marshals on hand to assist. Face coverings remain mandatory, especially where social distancing is limited.

Meanwhile, only those who are travelling will be allowed access to terminals to cut numbers, with Heathrow advising passengers to say their welcomes and goodbyes away from the terminal doors.

Additionally, passengers have been urged to ensure they arrive promptly for their flights – two hours in advance for short-haul, and three hours for long-haul – as well as to regularly sanitise their hands.

Kathryn Leahy, Heathrow’s airport operations director, said: “In the coming days and over the Christmas period, our terminals are likely to feel busy and we will need to manage this carefully.

"We are asking passengers to support us in maintaining social distancing, wearing face masks, and following the instructions of the additional Covid marshals we will have on duty."

The new measures will come into effect at terminals 2 and 5 on Wednesday (16 December) to coincide with London being placed under the country’s toughest Tier 3 Covid restrictions.

Heathrow added these interventions were further evidence of the need for government to get on top of mass testing.

"While the first step has finally been taken in ’test to release’ this week, more miles are needed to ensure passengers and airport workers can travel with confidence, kickstarting the economic fightback we need to start in earnest during 2021."