It is said of the ravens in the Tower of London that if they ever leave, Britain will fall.

But now their master has a radical new policy which allows the birds greater freedom - and one is even allowed to regularly fly away.

Chris Skaife, Raven Master at the Tower of London, has been trialling a new method of clipping the ravens' wings which allows one loyal favourite to leave the tower.

The bird, named Merlina, goes as far as the nearby wharf next to the river Thames. Unusually, she is "bonded" to the keeper - meaning she always returns.

It is believed to be the first time a raven has been allowed to leave since the birds were first kept to guard the Tower more than a century ago.