A pod of 40 whales spotted off the coast of Essex had to be shepherded to safety by police.
Essex Police's marine unit and helicopter were alerted to concerns the pilot whales might become stranded on beaches or sandbanks after being spotted close to shore.
Pc Simon Lofting, from the marine unit, said: "We have had small numbers of dolphins and porpoises off Essex but this is the first time so many whales have been seen.
"It was certainly one of our more usual operations and we all worked closely to ensure that the whales were not stranded in shallow water while chasing shoals of herrings."
Members of the charity, British Divers Marine Life Rescue, called police and coastguard when the whales were close to shallow water at St Lawrence Bay on Tuesday.
They spent the day shepherding the whales to safer waters and then monitored their movements throughout yesterday.
The special branch marine unit used a high speed boat to reach the scene and with local boats managed to turn the pod back towards the open sea.
The mammals, which were believed to be following and eating shoals of herring, were later seen heading towards the shore between St Osyth and Jaywick.
At one point the helicopter descended to about 200ft to "flag down" a local fishing boat that was heading straight for the whales, Essex Police said.
Pc Kevin Flinn, observer on the helicopter, said: "We hovered between the beach and the pod and were able to move closer to them until they turned and went back to deeper water.
"The whales were about five metres long and in very shallow water and with the tide receding.
"There certainly was a risk of them beaching on the sandbanks but we moved them away from danger. The marine unit boat and other vessels then took over and escorted the pod further offshore."
