Police said it was "too early to tell" what might have caused the collision, and were focusing on identifying the victims and informing their next of kin. Two people were killed in each aircraft.

 

Both the helicopter and light aircraft had taken off from the Wycombe Air Park, an airfield in Buckinghamshire where air traffic control had been shut due to "staff shortages".

 

A Notice to Airmen was previously issued to warn pilots that the airfield's air traffic control services would be closed during three 30-minute periods on selected days between Nov 7-30 due to a "staff shortage".

 

The crash occurred about half an hour after the latest closure was due to end. A spokesman for Wycombe Air Park, which often trains novice pilots, confirmed that both aircraft had come from the airfield.

 

The crash is understood to have involved a Cessna 152 which had suffered substantial damage to its landing gear, propeller and engine covering during a previous crash as it was taking off at Bodmin airfield, in Cornwall, in July 1993.

 

Wreckage from the aircraft tumbled from the sky and landed over the former home of the Rothschild banking family at Waddesdon Manor in Buckinghamshire.

 

Witnesses reported hearing a "loud bang" and a plume of smoke could be seen above trees.

 

The manor, which is a popular wedding venue and visitor attraction, is owned by the National Trust and managed by the Rothschild Foundation, chaired by Jacob Rothschild, 4th Baron Rothschild. A landmark British tourism spot, it attracts more than 390,000 visitors every year.

 

Local residents from the nearby village of Upper Winchendon stepped forward to offer assistance to the emergency services, feeling that the accident was very close to their lives.

 

One parent wrote on Twitter: "Nothing like your heart stopping when you learn that a plane has come down literally 500 meters from your toddler's nursery."

 

Another resident at the scene said: "It happened in woodland on the estate. I didn't see the crash but I heard it. There was smoke. It was clear there were unlikely to be any survivors."