Simpson simply proved too strong for Barrett

The Londoner, whose right eye was badly cut in the first, never looked like beating the count after being dropped to his knees with a vicious body shot.

Greenock's Simpson, 23, was making his first defence after winning the title from Andy Morris in December.

"It was a good punch. I've only stopped four people before but I felt my power was getting to Ryan," he said.

Barrett, 24, from Thamesmead, had only been stopped once previously.

That was when he stepped up two divisions and was beaten in one round by Olympic lightweight silver medallist Amir Khan last September.

I'd trained for a longer fight but I could feel I was hurting him when I got in close John Simpson

He bounced back with three straight points victories, including a win over ex-British champion Jamie McKeever in February to secure his title shot.

But beating Simpson at London's Millennium Hotel proved a step up too far for the rangy 5ft 10in southpaw.

Barrett suffered a serious setback when a clash of heads left him with a nasty cut in the corner of his right eye in the opening round.

The taller Barrett's best chance was to use his reach advantage and box behind his jab.

But the compact Simpson worked his way inside to land some punishing body shots.

The champion said: "I'd trained for a longer fight but I could feel I was hurting him when I got in close."

Simpson now hopes to target the European title but he added: "It would be nice to keep defending the Lonsdale belt and win it outright."

He took his record to 15 victories - five of them inside the distance - from 20 fights, while Barrett lost for the fourth time in 20, with one draw.