A DOCTOR involved in controversial research linking the MMR vaccine with autism has defended his work at a medical tribunal.

Professor John Walker-Smith, of Monkhams Drive in Woodford Green, along with colleagues Prof Simon Murch of Tooting and Dr Andrew Wakefield, who now lives in the USA, all deny serious professional misconduct.

The General Medical Council tribunal heard how the men carried out "invasive" procedures on young children - spinal taps' and colonoscopy procedures - while investigating their theory that the measles, mumps and rubella vaccine (MMR) could be linked with a rise in cases of autism in the UK.

The hearing was told of previous cases when some doctors had rejected such painful methods as unnecessary.

Taking the stand, Prof Walker-Smith said: "None of the tests would have been conducted if they were not considered necessary.

"I was fascinated by the possibility that something might be done to unearth what was going on, and in the future down the line to help the children in their plight."

He added: "But that was secondary to the primary concern of getting care for them."

The doctors' original research attracted huge controversy when it was first published in medical journal The Lancet back in 1998.

Their influential claims led to a drop in the number of parents putting their children forward for the vaccine nationwide, and in Redbridge the numbers receiving the MMR jab dropped from 90 per cent in 1998 to a low of 72 per cent in 2005, coinciding with a steep rise in the number of cases.

The men's findings have since been emphatically rejected by bodies such as the British Medical Journal, the Medical Research Council and the Department for Health.

Co-defendant Dr Wakefield also stands accused of paying children at his son's birthday party £5 each for blood samples while he was conducting his research and "joking" about it afterwards at a medical conference.

Outside, dozens of protestors fiercely defended the doctor and his research, claiming he was the victim of a "witch hunt".

The men face being struck off the medical register in the UK if found guilty.

The hearing continues.