An expert witness said he was unable to explain how the gun Mark Duggan was allegedly holding when he was shot dead ended up 20ft from his body.

Mark Duggan's shooting by armed police in August 2011 sparked the Tottenham riots and looting around the UK.

Professor Jonathan Clasper, a military surgeon who examined Mr Duggan's body gave evidence to the inquest into his death this morning.

He told the jury it was "very difficult" to explain how the gun got to the place it was discovered if the 29-year-old was holding it when he died.

Mr Duggan was shot and killed by a police marksman after the minicab he was travelling in was stopped by police officers in Ferry Lane, Tottenham, on August 4, 2011.

Previously, the officer claimed he opened fire in self-defence after he saw Mr Duggan point a gun at him.

Two shots were fired – one which went through Mr Duggan’s chest and one which passed through his bicep. However, when police searched his body they found no gun.

A gun wrapped in a dark sock was later recovered in a grassy area behind a wall between ten to 20 feet from Mr Duggan's body.

During the inquest, it has been suggested that the gun ended up there due to some involuntary movement made by Mr Duggan.

One theory was that the force of the bullet hitting the 29-year-old’s arm would have caused him to throw the gun.

But this morning, Prof Clasper said this scenario is unlikely as a reasonable degree of force would be needed for this to happen.

He said: “It is unlikely that being shot in the arm would have caused the gun to end up in the grass by some involuntary movement.

“The bullet did not have enough energy to cause that to happen.”

The marksman who killed Mr Duggan claimed he had his eyes “glued” to the gun throughout the incident.

He claimed he saw the gun when he fired both shots and when Mr Duggan fell to the ground.

Leslie Thomas, the lawyer representing Mr Duggan’s family, asked Prof Clasper if, given the evidence, he could explain how the gun came to be in the grassy are.

He said: “No, it would be very difficult to explain how the gun ended up where it ended up.”

Prof Clasper added that the shot to the arm would not have meant Mr Duggan would drop the gun.

He said: “People don’t respond to bullet wounds the way you would expect them to – because of the adrenaline in many cases people don’t notice the injury.

“If he was moving his arm he would continue to move his arm even after he was shot.”

Ian Stern, the lawyer representing the armed police officers, suggested that had Mr Duggan started throwing the gun before he was shot he would have continued to do so after sustaining two bullet wounds.

Prof Clasper agreed with this and said: “In his statement, [the officer] describes a flinching action which could have been Mark Duggan throwing the gun.”

Mr Thomas pointed out that the flinching movement had been after the first shot and the marksman claimed Mr Duggan was holding the gun when fell to the ground.

He added: “No one, not one police officer or witness, has said that they saw Mark Duggan make any sudden or jerky movements or make any attempt to throw a gun.”

The inquest continues.