Caught on camera as it rushes upstream, a tidal wave rolls up the Ouse at a rate of knots, as nature shows she is still a force to be reckoned with.

When the moon's right over the Fens and the biggest tides turn from ebb to flood, great forces awake in The Wash.

They drive a wave that can be a metre or more high all the way inland to Denver.

Police officer turned environmentalist Kevin Holland became intrigued by the folklore of the Fens when he moved to Magdalen seven years ago.

Since then, he has documented the Eagres - as fenfolk call the tidal waves.

'One of the old boys in the village told me the formula,' he said.

'By cross referencing a few charts and time tables, we can predict with great accuracy the exact moment when a thunderous torrent of white water will crash along the banks and charge up river.

'On occasions, the Wiggenhall wave is no more than a gentle rolling wall of water, rolling so fast that it would take some very fit people to out run it for any great distance.

'Some times, if you are really lucky, you'll get the Eagre Tide. A force so powerful legend has it, that the Fens giant Thomas Hickathrift was wading through the river behind the blacksmith's, catching seals for his tea, when the Eagre came up and it carried him to Ten Mile Bank.'

More recently surfers have appeared and tried to ride the wave. Mr Holland hopes to attract more visitors to the village on wave watching trips.

The next Ouse Eagre is expected on July 29. Cornish surfers who have seen Mr Holland's videos on YouTube are hoping to travel up to Norfolk for the occasion.