A nephew and his uncle were jailed for 57 years for the failed execution of a relative.

Roger Khan, 57, and his nephew Mohammed Ali, 39, travelled down from their home in London to carry out the murderous attack on restaurant owner Nasim Ahmed as he arrived at his home in Newton Abbot, one night in October 2010.

Nothing was said as the pair, armed with a metal bar and a knife, stabbed and struck father of two Mr Ahmed, Exeter Crown Court heard.

The assault only stopped when the victim's wife Alhala Khatun heard his cries for help and her screams alerted neighbours and the two men ran off.

Judge Graham Cottle jailed Khan for 30 years and Ali for 27 years after they were convicted of attempted murder.

The judge said the pair attacked Mr Ahmed, who had been accused of an historic sexual offence against a female member of the family, but no complaint made to police until after the Devon attack.

Jailing the pair, Judge Cottle said: 'I have no doubt that it was this unproven allegation that was the motive behind your murderous attack.

'This was effectively an execution. I have no doubt that as you hurried away into the night you believed that you had done more than enough to carry out your joint plan to kill Nasim Ahmed.'

The judge said it was a premeditated and planned revenge attack which left the victim with a dreadful injury and his family in fear of reprisals.

The judge said the knifeman – it is not known who was armed with the knife which was never found – intended to cut Mr Ahmed's throat, but in fact sliced his face three times before running off.

A hospital consultant said Mr Ahmed's wounds ranked among the worst he had seen in his 18 years' experience.

Prosecutor Malcolm Galloway told Exeter Crown Court that in the latter part of 2009 an allegation was made within the extended family that 'the victim Nasim had sexually assaulted a younger family member' – that allegation was reported to the police only after the attack took place, but has since been withdrawn by the woman.

'The jury may well conclude that this sexual allegation and the subsequent demands for money from the victim Nasim Ahmed and his family, which they refused to comply with, are the probable motive for the attack upon him,' he said.

One night last October, the pair drove down together in a silver BMW from London to Newton Abbot and attacked Mr Ahmed as he returned home from work at his restaurant in Teignmouth.

Mr Galloway told the jury: 'The two men were armed with at least a metal bar and a knife.

'The blows and stabs were aimed at the head and face and neck area of Mr Ahmed.

'Nothing was said by the two men as they brutally attacked Mr Ahmed.

'There were no demands for money or indications as to what he must do to persuade the men to stop attacking him.

'The attackers actually ignored the night's takings which had fallen to the pathway during the attack.

'The attack only came to a stop due to Mr Ahmed's wife, who having heard her husband's cries for help, screamed, which alerted the neighbours and the two men ran off.'

Mr Galloway said he had suffered a fractured skull and 'he was lucky to be alive'.

Khan, of Dacre Acre Park, London, and his nephew Ali, of Brokenbury Street, London, both denied attempted murder of Nasim Ahmed – Ali is his brother-in-law – but were convicted after a four-week-long trial.

Khan has previously served 12 years for armed robbery and four years for knifing two fellow prisoners.