Prof Ged Martin recalls a tragic clash between RAF pilots 80 years ago

Around 6.15am on September 6, 1939, three days after the outbreak of the Second World War, Britain's new radar defence system detected incoming aircraft crossing the Essex coast. A false alarm, it was mistaken for an enemy air raid.

Fighter Command scrambled Spitfires from RAF Hornchurch and also Hurricanes from North Weald.

Without orders, two young North Weald Pilot Officers, Frank Rose and Montague Hulton-Harrop, jumped into their Hurricanes and followed.

Putting enthusiasm before discipline, they chased the main body of fighters. Flying at a lower altitude, they were spotted by a flight of three Hornchurch Spitfires.

None of the pilots had been in combat. They were flying into cloud and early morning sun. The RAF was experimenting with transponders, which emitted and received bleeps - an electronic signal identifying friendly aircraft. They hadn't been fitted to these planes.

With top speeds of over 300 mph, British fighters flew a mile in 12 seconds.

Pilots could only rely on instant visual recognition.

The elegant Spitfire was easy to spot.

The workmanlike Hurricane resembled the German Messerschmitt 109.

The three Spitfires were commanded by a South African, "Sailor" Malan. (He needed a nickname, however silly, because his parents had unfortunately called him Adolph.) There would be controversy over what happened next.

Mistaking the two stray Hurricanes for German aircraft, Malan used the radio telephone to order the attack, "Tally Ho!"

He also claimed he realised his blunder and immediately radioed, "Friendly aircraft! Break away!"

But Pilot Officers Paddy Byrne and John Freeborn insisted they never heard the command to stop. They opened fire.

Pilot Officer Rose survived a crash-landing.

But Montague Hulton-Harrop, shot in the back of the head, was dead before his Hurricane hit the ground. Aged 26, he was the first RAF casualty in World War Two, the victim of what appalling military jargon calls "friendly fire".

Although the story was banned in Britain, newspapers in the still-neutral USA reported the shambles.

The encounter was derisively nicknamed "the Battle of Barking Creek", a joke location roughly about half way between the two airfields.

In fact, the action had happened near Colchester.

A court-martial acquitted Byrne and Freeborn. Some alleged that Malan had lied about trying to stop the attack to protect himself. Certainly, communications between pilots needed improvement.

The only positive thing about the Battle of Barking Creek was that it forced the RAF to develop efficient aircraft identification systems before the summer of 1940.

In those desperate days of the Battle of Britain, Fighter Command, "the Few", needed every aircraft to resist the Nazi onslaught.

Frank Rose returned to the skies, and was killed defending France in May 1940. Paddy Byrne was shot down over occupied Europe and taken prisoner. He persuaded the Germans that he was mad. In 1944, they handed him to the Red Cross which repatriated him through neutral countries to Britain. He rejoined the RAF, but was not allowed to fly - in case he fell into Nazi hands again.

With 27 "kills" to his credit, Sailor Malan later returned to South Africa, where he regarded white racism as just another version of the fascism he'd fought in Europe. He led a mass protest movement called the Torchlight Commando, and is regarded as a hero of the campaign against apartheid.

Like Malan, John Freeborn fought desperate actions over Dunkirk to protect British troops on the beaches. He twice won the Distinguished Flying Cross, but left the RAF in 1946, disillusioned by the "nincompoops" in command.

In 2009, confined to a wheelchair and within a few months of death, John Freeborn made an emotional visit to Montague Hulton-Harrop's grave.

"I think about him nearly every day," he said.

"I've had a good life, and he should have had a good life too."

The grave, facing the war memorial in the churchyard at North Weald, is honoured and cared for by the respectful local community.