The family of a footballer left in a coma by a savage beating have formally complained to the Metropolitan Police after two serving officers went into business with one of his attackers. 

Maggie Hughes, mother of former Croydon Athletic and Sutton United player Robbie Hughes, was "disgusted" to learn police constables Glen Oliver and Leanne Henery were running a gym with Daniel Bell, one of four men convicted of the vicious battering that nearly killed her son. 

The family have been supported by officers from Sutton station, where PC Oliver works, during their fight for justice following the attack in Malia, Crete, in 2008.

Ms Hughes, 61, is furious and incredulous that the Met, which must approve officers' second jobs and business interests, sanctioned the Crossfit gym in Crawley despite Bell, 26, being on bail awaiting the retrial and his station's links to the case.

Your Local Guardian: Attacked: Mark Hughes with his mum, Maggie

Maggie Hughes is angry her son Robbie's attacker has been allowed to set up a business with two police officers

Bell and PCs Oliver and Henery, who are partners and live in Croydon, are all directors of the firm, which they established in December last year. 

PC Oliver and Bell are both also fitness instructors at the gym, which counts other serving officers at members.

Ms Hughes, who learned of the business this month, said: "It is disgusting. When I first found out I thought it couldn't be true.

"Something needs to be done about it. This is not right. This doesn't send out a good message to the public, that our law-abiding police force is going into business with known felons."

Senior Met officers have launched a probe into the business after receiving Ms Hughes's complaint. 

A force spokesman said: "The full details of this business interest are being reviewed by senior officers. Until this review is complete we are unable to comment further."

A spokesman for the gym said: "We feel that it is quite sad that a business that exists purely for the benefit of others is being targeted due to the alleged actions of one of the founding partners over six years ago.

"The case this relates to had numerous defendants and Daniel is still undergoing the appeals process to protest his innocence regarding his alleged involvement in the incident." 

Bell and friends Curtis Taylor, Sean Branton and Joseph Bruckland, all of Horley, Surrey, appealed convictions for causing grievous bodily harm after being handed suspended sentences by a Greek court in 2012. 

Their retrial was scheduled to begin on Wednesday but was postponed until September 30 due a lawyers' strike, meaning 33-year-old Mr Hughes's fight for justice will now enter a seventh year. 

His mother described the delay, which means £8,000 spent by the family on accommodation and travel for themselves and witnesses went to waste, as "a slap in the face".

She said: "I’m totally worn out. There’s been no rush to get this case sorted and it will be seven-and-a-half years after the incident when the trial finally happens."

That fight will now go into a seventh year after the retrial of the four men, convicted of causing grievous bodily harm at a Greek court in 2012, was adjourned for the second time last week.

Bell, Curtis Taylor, Sean Branton and Joseph Bruckland, all of Horley, Surrey, were scheduled to stand trial on Wednesday but will now face court on September 30 next year.

Ms Hughes, 61, described the delay - caused by a lawyers' strike and cost her family and witnesses £8,000 in travel and accommodation - as "a slap in the face". 

She said: "I’m totally worn out. There’s been no rush to get this case sorted and it will be seven-and-a-half years after the incident when the trial finally happens."

Mr Hughes spent two months in hospital and was left permanently brain-damaged after the four attackers struck him with a broken bottle, stamped on his head and left him for dead outside a nightclub while on holiday.