BORIS Johnson will return from COP26 to London by plane – despite leading global efforts to cut carbon emissions.

Downing Street has defended the decision to use aviation instead of travelling by train.

The Prime Minister’s official spokesman confirmed Mr Johnson will fly back to London from Glasgow when the leaders’ conference section of the summit ends this week.

Pressed on why the Prime Minister could not go by train for a journey within the UK, the spokesman said it was important he was able to travel round the country while facing “significant time constraints”.

He said the private charter jet he is using for the flight uses a special mix of “sustainable” aviation fuel and is one of the most carbon-efficient aircraft of its size, while the emissions will also be offset.

It produces less than half the emissions produced by the RAF Voyager which the Prime Minister sometimes uses for foreign travel.

“Our approach to tackling climate change is to use technology so that we do not have to change how we use modes of transport, rather we use technology on things like electric vehicles so that we can still get to net zero,” the spokesman said.

“That has very much been at the core of our approach.”

“It is important that the Prime Minister is able to move round the country and obviously we face significant time constraints.

“The plane the Prime Minister used on his travels is one of the most carbon-efficient planes of its size in the world. It produces 50% less CO2 emissions than, for example, the larger, Voyager plane.

“It uses a specific type of fuel that is a blend of 35% sustainable aviation fuel and 65% normal fuel, which is the maximum amount allowed.”

Mr Johnson used the aircraft, operated by Titan Airways, to fly out to the G20 summit in Rome on Friday and then carried on to Glasgow on Sunday.

The disclosure came after Chancellor Rishi Sunak faced accusations of hypocrisy when he announced a cut in air passenger duty on short-haul flights and a further freezing of fuel duty in his Budget last week, just days before the opening of COP26.