HMS Cattistock broke off from fish duties to return to her true purpose – blowing up mines.

The Portsmouth-based minehunter is currently assigned to the Fishery Protection Squadron, but she scurried to the Suffolk coastline after a fisherman thought he snared a mine off Felixstowe.

The trawler lowered the warhead back into the sea then raised the alarm. Cattistock spent 24 hours sweeping the seabed with her 2193 sonar.

When it picked up a strong contact, the ship sent down her robot submarine to investigate.

“Visibility on the seabed was terrible and the operation wasn’t helped by strong winds and tides,” said Cattistock’s CO Lt Cdr James Barnes.

Eventually the outline of a German GC influence mine in remarkable condition appeared on the video screen in the operations room.

A diver attached a 4lb charge to the weapon, then returned to Cattistock which withdrew to a safe distance as the mine was exploded, sending a plume of water 80ft into the air.

Barely had the ship finished her mine disposal duties than she resumed fishery protection work.

As the ship approached a British trawler close to Holland, the vessel upped nets and began to scarper. Cattistock gave chase and passed the fishing boats details on to a nearby Dutch fishery protection craft.

The Netherlanders stopped the errant trawler; their inspection team found a substantial haul of undersize fish aboard; a prosecution is impending.