Fears that a great white shark could be stalking the waters off the Norfolk coast have been downplayed by an expert.

Concern was raised after a walker recently found a 5ft porpoise with chunks taken out of its head and tail at Horsey, near Great Yarmouth.

Dr Ken Collins, a shark specialist at the University of Southampton, said the injuries definitely appeared to be inflicted by a shark.

However, he said the shark responsible would have been a much smaller species - such as a shortfin mako - and there was no need for alarm. The presence of sharks near a seal colony was not surprising.