"Within two weeks he had lost his speech and started bumping into the furniture. He seemed to lose his sense of balance. Then he became more and more withdrawn. He didn't appear to be listening." Eventually autism was diagnosed, and he also developed bowel problems.
Mr Miles, 42, of west London, said: "We have a video of Robert before the vaccination and there is no question of him having had any signs of the disorder earlier which were unrecognised. We are convinced it was caused by the MMR vaccination."
Matthew Poulter was 15 months old when he was vaccinated with MMR. His mother Rochelle, of Brighton, said: "He had been a sociable child but his speech just stopped. He was not saying anything, just grunts and moans. I am convinced it was the MMR. There was no other trauma that could possibly have caused it."
Both Matthew, now aged seven and Robert, now aged nine, have been granted legal aid to sue the manufacturers of the vaccine. Theirs are among 300 cases being handled by Richard Barr, a partner in Norfolk solicitors Dawbarns. Mr Barr said: "We have been approached by 1,300 families and we are processing cases as fast as we can."