A helicopter joined a major search operation off the Kent coast last night after an SOS signal was activated.

Lifeboat crews were seen scouring the coastline between Broadstairs and Deal last night after reports a personal locator beacon had been activated.

The helicopter was originally searching a 50-mile area after it was called shortly before 10pm, but that was soon reduced to five miles.

The RNLI conducted a stepped shoreline search from Sandown Castle near Deal, up to North Foreland and back, before the personal locator was found ashore, and the operation was stood down.

A personal locator beacon is a small device that sends a personalised distress signal to search and rescue services when activated.

A spokesperson for the charity said: “Due to it being a new crescent moon, the night was very dark so the search was carried out using radar, searchlights and the VHF direction finder in the calm sea.

“A coastguard helicopter was launched to aid the search, alongside the coastguard mobile teams as it was uncertain whether the beacon had been activated in the sea or on land.”

At 12.30am, the personal locator beacon was found by the helicopter.

An RNLI spokesperson added: “The volunteer crew of the Diamond Jubilee were glad to return home as it had been a long day.

“Earlier that day they had been on a training exercise and had only finished the session at 8pm that night.”

Personal locators are used at sea as well as ashore and can be used on their own or in conjunction with a mobile phone.

They are useful when people are out of range of cell phone service.