Dramatic CCTV footage of a sea rescue, in which a police officer saved a 13-year-old boy, has been released.

The boy got into trouble while swimming in the sea off Southend, after travelling to the Essex coast with his stepmother from their home in Middlesex.

PC Martin Knights, 46, and a colleague were on a routine patrol nearby when they saw the teenager struggling in the water.

The brave police officer removed his uniform and plunged into the sea to rescue the boy.