Dorset Police have apologised for a catalogue of errors after a Corfe Mullen teenager was wrongly jailed for allegedly brandishing a knife in a busy pub.

George Nethercott, 19, was locked up for 18 months when a jury decided it was he who had “run amok” with an eight-inch blade in the Dorset Soldier in February 2009.

But top judges sitting at London’s Appeal Court last week quashed the conviction and slammed the “incompetence” of the police investigation.

Errors included lost CCTV footage and a failure to track down other possible culprits.

Detective Superintendent Garrick Smith, head of criminal justice for Dorset Police, said there were “no excuses” for the failures.

“Victims and the criminal justice system expect the highest standards in the quality of our investigations and we fell below these,” he said.

“Sometimes individual officers make mistakes, but what is very rare is for a number of officers to make individual errors in a single case. Unfortunately this is what happened in this case.”

Lord Justice Rix said individually the errors would not have led to the conviction being unsafe, but collectively they did.

Det Sup Smith said changes were being made in the way investigations were managed to ensure there would be no repeat of the errors.

Mr Nethercott spent three months behind bars after he was initially convicted for affray and possession of a bladed article at Bournemouth Crown Court on December 23.

The teenager, who always denied the attack, told the Echo he was now looking forward to a fresh start.

“I was very disappointed to have been found guilty by the jury last year and then to be sent to prison, knowing I was innocent,” said Mr Nethercott.

“I am pleased at last that the Appeal Court has quashed publicly the conviction and I hope to resume my life in the community as quickly as possible.”

Bournemouth Crown Court had heard how a teenager had chased the landlord around the Wareham Road pub with a blade after he refused to serve him alcohol. He was eventually forced out of the pub, the jury was told.