A surgeon performing a knee replacement put in the wrong implant, it has emerged.

The patient had surgery at Gorleston's James Paget University Hospital in September.

But according to papers presented to the hospital's board of directors the implant meant for the right knee contained components for the left.

The error is classed as a "never event" - one so serious it should never be able to happen.

James Paget University Hospital director of nursing Julia Hunt said: "The trust was made aware, via the National Joint Registry, that a right knee replacement had been undertaken that contained a left tibial component - a never event under the category of wrong implant/prosthesis.

"A right knee replacement should contain a right tibial component.

"An initial review of the case has confirmed the patient has come to no harm, and a full root cause analysis investigation has been undertaken."

She confirmed no extra surgery was required, and the patient was being kept fully informed and monitored on an ongoing basis.

"As with any serious incident or never event, we carry out a full investigation to find out how and why this occurred, to identify what can be learnt from the incident and whether any procedural changes are required," she said, adding: "In the meantime, immediate actions have been taken including a review of our five steps to safer surgery process."

It is the second serious mistake to be reported this year.

In March papers revealed a feeding tube had been wrongly inserted in a lung.The target for the number of such events is zero.

Details of the incident were revealed ahead of the board's November meeting which included updates on performance.

Figures for September reveal the trust achieved just over 66pc of its measurable indicators, failing just over 33pc.

The report said the month had been "challenging" with a sustained increase in attendances.

In A&E fewer patients were seen within the four-hour target than in August.

The hospital said the level of demand added to pressures with some 7,033 patients presenting, and 1,879 arriving by ambulance in that month alone.