Theresa May has described the “extraordinary sight” of a British Typhoon jet tipping its wing to reveal its weapons, in an experience she said left her “immensely proud” of the Royal Air Force.

The Prime Minister was speaking publicly for the first time about the incident as she hosted a reception at Number 10 to mark the centenary year of the formation of the Royal Air Force.

Recalling the “extraordinary moment” which she experienced during a flight back from Cyprus, Mrs May said her plane was intercepted by two RAF Typhoon jets which “pulled up alongside”.

Tipping their wings to reveal their weapons, Mrs May said: “It was the most extraordinary sight and a true heart in mouth moment.

“And although I knew it was a mock exercise, at least I think it was a mock exercise, I was given a rare glimpse into what it must be like in a Russian aircraft probing UK airspace or an airliner not responding to air traffic control.

“No one who has witnessed such a moment will ever doubt the skill, the rapidity of response or the might of Britain’s Royal Air Force, and it made me immensely proud.

“Proud not only of our impressive military force, but of the skill, courage and dedication of our air men and women who for 100 years have so valiantly defended our skies and kept our enemies at bay.”

In the garden of her Downing Street residence, personnel and the heads of all three UK military services gathered alongside veterans, civil servants and politicians including Defence Secretary Gavin Williamson and defence minister Tobias Ellwood.

A life-size replica of a Red Arrows jet was also parked on the street outside, and as Mr Williamson made his way into the event, he joked that no one would give him the keys to the red aircraft.

Mary Ellis, one of the last surviving pilots of the Air Transport Auxiliary, who delivered flew spitfires and Wellington Bombers during the Second World War was also a guest at the reception.

The 101-year-old who joined the ATA in 1941, delivered more than 1,000 aircraft to the Royal Air Force – and chatted to Mrs May about her service.

During her speech to the 150 guests, Mrs May also said in an “increasingly uncertain world” the skill and courage of the RAF is “vital to the air and space power that allows the UK to respond quickly and decisively around the world”.

She added: “Whether that is mounting immediate disaster relief or an evacuation operation, as we did in the Caribbean last autumn, fighting Daesh in Syria and Iraq as the second largest contributor to air operations in the region, or conducting a long range precision strike mission in a matter of hours as we did Syria last month – one of the gravest decisions I’ve ever taken as Prime Minister.”

It was 100 years ago, on April 1 1918, that the Royal Flying Corps and the Royal Naval Air Service merged to create the RAF – the world’s first independent air service.

World War II Air Transport Auxiliary pilot Mary Ellis was a guest at the reception (Jonathan Brady/PA)
World War II Air Transport Auxiliary pilot Mary Ellis was a guest at the reception (Jonathan Brady/PA)

Mrs May said during the past century the RAF has “proved it is not only the first independent air force in the world, but also the finest”, and stands “shoulder to shoulder” with the Army and Royal Navy to defend the UK.

Chief of the Air Staff Air Chief Marshal Sir Stephen Hillier, echoed this sentiment and said the origins of the RAF lie in the Army and Royal Navy, and the formation of the RAF relied on those with the vision to deliver air power through a unified air force.

He said “strong political leadership brought that vision to life”, adding: “But the military vision did not come from the RAF – how could it have?

“It came from the Army and the Royal Navy. I should point out the most senior leadership of the Army and Royal Navy at the time were not wildly enthusiastic about giving up their air capabilities and passing them on to a new service, but let’s leave that to history.”

He said the RAF “owes an immense debt” to those who were formerly in the Army and Royal Navy, adding the centenary could not be celebrated without both services for the foundations they laid.