A consultant surgeon has been convicted of the manslaughter of a patient at a private London hospital and sentenced to two and a half years in prison.

David Sellu, 66, was found guilty of manslaughter through gross negligence over the death of James Hughes, who died three days after developing a life-threatening condition while undergoing treatment in 2010.

Hughes, 67, died at the Clementine Churchill Hospital in Harrow, north-west London, following knee replacement surgery. The operation went smoothly but while recovering from surgery he developed abdominal pain and was transferred to Sellu's care.

Sellu suspected there had been a rupture in the patient's bowel – a potentially life-threatening condition that requires surgery – but the surgeon ignored the urgency that the case demanded and the patient later died.

The judge at the Old Bailey, Mr Justice Nicol, said that Sellu had failed to give instructions to prescribe antibiotics and should have carried out and examined abdominal scans of Hughes far earlier.

In his sentencing remarks, the judge said: "Even if you had acted more speedily, there was a chance that Mr Hughes would have died anyway. There is always such a risk with major abdominal surgery of the kind he needed.

"But the chance would have been very, very much smaller if you had acted as a reasonable surgeon would have done on the Thursday night.

"The risks would have increased if the operation had not taken place until Friday morning and would have got progressively larger as the day went on, but at each stage the chances of his survival would still have been better than when he finally did get to the operating theatre late in the evening of Friday 12 February."

He added: "It was you who was responsible for determining his treatment. It is your several failures in that regard which amounted to gross negligence. I am afraid that it means your culpability is high. And that negligence contributed significantly to the death of Mr Hughes."

Elizabeth Joslin, a specialist lawyer for the Crown Prosecution Service, said: "James Joseph Hughes was in hospital for knee surgery when he by chance suffered a perforated bowel. David Sellu's care fell far below the expected standard, with terrible consequences.

"Prosecution of doctors for gross negligence manslaughter is rare and the threshold for criminal prosecution is high, but this doctor's actions were not mistakes or errors of judgment, but negligence so serious that he has now been convicted of a criminal offence. Our thoughts are with the family of Mr Hughes."

His wife, Ann, described the suffering experienced by the family in a victim impact statement put before the court. It said: "For three years we have struggled to discover and then accept the truth of what happened to Jim. The world does not stand still but for us we have been subjected to a tortuous purgatory that can only be brought to an end by truth and justice.

"Our trust in normal processes, authorities and structures of society was shattered by the inexplicable, callous and deceitful actions of the medical profession entrusted with the most basic responsibility to protect human life."