A pilot most likely crashed into a reservoir on purpose after suffering with his mental health, investigators have concluded.

Peter Beeson, 66, from Bishop's Stortford in Hertfordshire, was killed instantly when his Beagle B121 Pup aeroplane hit the water.

It happened at Hanningfield Reservoir, near Chelmsford, at about 14:00 GMT on 28 December.

Beeson had told a friend he felt "rubbish and unhappy" in the days before his death, the Air Accidents Investigation Branch (AAIB) said in a report.

The pilot - who had 20,000 hours of flight experience - took off from North Weald Airfield in Essex at 12:39 and circled the reservoir for 70 minutes.

Witnesses described seeing his plane, which he had owned for nine years, plummeting nose-down before hearing "a big splash and a loud bang".

Beeson's body was found by police divers at a depth of 6m (19.6ft) two days later.

"The pilot had been experiencing mental health issues and sleep difficulties for a few weeks before the accident," the AAIB wrote.

"Based on this information, a handwritten card by the pilot and the aircraft's flight profile, it is likely that the pilot deliberately flew into the reservoir."

Beeson flying solo was described as "extremely rare" by a friend, who was due to meet him for lunch that day.

He said the pilot seemed "quiet and vacant" when they last met on Christmas Day.

Beeson had been under the care of a consultant psychiatrist, who diagnosed him with mental health issues and sleeping difficulties.

Investigators also noted that on Christmas Eve, Beeson had flown alone over Hanningfield Reservoir.

"While it could not be determined what the pilot's intentions were that day, the flight profile was similar to the accident flight," they wrote.

The AAIB said there was "no evidence of a pre-impact failure" of the aircraft.

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