Colin Farrell has revealed that his four-year-old son James suffers from a rare form of cerebral palsy that affects his speech and mobility.

The Irish actor spoke publicly for the first time about the “amazing courage” his son has shown in the first four years of his life, despite being born with Angelman Syndrome.

He said: ”With my son the only time I'm reminded that there is something different about him – that he has some deviation of what is perceived to be normal – is when I see him with other four-year-olds.

“Then I go “oh yeah” and it comes back to me. But from day one I felt that he's the way he's meant to be.”

Farrell – who shares custody of James with his mother Kim Bordenave – also told of his pride at the advances his son has made.

“He took his first steps about six weeks ago and it was four years in the making,” said Farrell. “All the work is his, he worked his arse off for four years.”

“And when he took the first steps it was incredibly emotional, there wasn't a dry eye in the house.”