Kevin Olsen, coastguard rescue officer for Lytham, was conducting a routine patrol on St Annes beach when he realised something was not quite right.

The sea, instead of gently ebbing and flowing, had stopped in its tracks, and there was no familiar sound of splashing as the water lapped onto the sand.

When Mr Olsen went to investigate on Saturday morning, he was astounded to discover the sea had frozen over for more than a one-mile stretch.

Mr Olsen said: "At about 10.30am on Saturday, I was doing a routine patrol on the beach, near St Annes Pier.

"At first I thought there was a foam substance at the edge of the sea, as there was about a 3ft wide layer of this white substance, which wasn't moving at all.

"When I got closer, I realised it was the sea, which had literally frozen in its tracks. I've been a coastguard for a number of years, and always lived by the sea, and I've never seen anything like it.

"Behind the white ice, there was a dark patch stretching back about two metres, where the sea had frozen. It was cold, but at four or five degrees it wasn't the coldest its ever been."

The only other known recent occasion when the sea has frozen was in Poole, Dorset, on January 7.

Scientists believe the phenomenon is due to low salt content and shallow depth.