A prisoner, caught swapping intimate text messages with his wife and mistress from behind bars, has been rewarded with an extra year in jail for his troubles.

Convicted gunman Clayton McCalman, 24, sent the saucy pictures to Masai St Aubyn-Agoreyo, 25, and Monica Merrin, 31, both from Tooting, using a smuggled mobile phone from inside Wandsworth prison.

McCalman, from Stockwell, was originally jailed for 10 years after a stand-off with armed police on Mitcham Common in October 2011.

He had been under surveillance by Operation Trident officers, who suspected he was involved in buying and selling firearms.

McCalman ran into a wooded copse area where he discarded a loaded semi-automatic pistol and then surrendered himself to the officers.

He was jailed at Kingston Crown Court in April last year after admitting to possessing a firearm with intent to endanger life.