A drowning fisherman who had been thrown out of his boat when it was hit by a freak wave was rescued by a Royal Navy helicopter crew just as his head disappeared under the water.

In a dramatic operation yesterday afternoon, dozens of onlookers powerless to help feared the worst as fisherman Stuart Williams started to sink beneath the surface a short distance off Porthleven in West Cornwall.

Aircrewman Petty Officer Shaun Knights was on board the Sea King helicopter, which had been scrambled from nearby RNAS Culdrose.

He said the situation initially looked bleak as the powerful helicopter hovered overhead.

"His face was under water.

"It was very time critical. I think if we had been even another minute later on the scene and it would have been a very different outcome."

The fisherman, who has not yet been named but is understood to be from Porthleven, was in the 23feet boat with a colleague when the boat was struck by a giant wave and capsized.

One man struggled ashore but the second was caught in the surf and unable to get to the beach.

PO Knights said: "We could see the crates and trays from the boat in the water and the fisherman in the middle of it.

"He had been in the water for about 20 minutes and he was very, very tired."