A crooked prison guard who teamed up with a jailed drug boss to flood Pentonville jail with cannabis and mobile phones has been jailed for five years.

Richard Carew, 32, was arrested after his colleagues found more than three quarters of a kilogram of marijuana in one wing of the prison on a single day.

The thriving black market in drugs and phones inside the jail in Caledonian Road, Holloway, was masterminded by inmate James Mansbridge, 36.

Carew was jailed for five years and Mansbridge for four at Southwark Crown Court today after they both admitted their roles in the drug plot.

Mansbridge’s cellmate Peter Henderson, 28, was jailed for six years - three years for his role in the prison drug gang and a further three for robbing a cash in transit van while on bail.

Their girlfriends Leanne Angel and Samantha Patten, both 25, received suspended prison sentences after they admitted laundering the proceeds of their partners’ dealing.

Judge John Price described drug dealing behind bars as “endemic and epidemic” adding “the prison authorities have a dreadful job in trying to stop this sort of thing going on.”

Turning to Carew, he said: “The reputation of the prison service is high, and when you let down the service, everybody suffers.”

Prosecutor David Durose told the court that in January last year a prison officer entered the cell of an inmate called Alan Merry, 25.

Mansbridge left the room and a package was found on the floor containing 234 grams of cannabis resin and 241 grams of herbal skunk cannabis.

A further 241 grams of skunk was found on the same day in the “chiller room” just outside the prison kitchens.

Carew’s fingerprints were found on both the plastic bag and parcel in Merry’s cell, while further analysis showed that the packaging around drugs found in the cell and in the kitchens came from the same manufacturing batch.

Prison officers also seized diaries belonging to Henderson and Mansbridge, which provided details of their payment system whereby punters asked their relatives on the outside to make transfers into bank accounts operated by Angel and Patten.

Carew, of Celt Close, Kemsley, Kent, Mansbridge, of HMP Whitemoor, and Henderson, of Downing Road, Dagenham, admitted conspiracy to supply Class B drugs and conspiracy to convey articles into prison.

Carew further admitted conspiracy to commit misconduct in a public office and transmitting images or sounds from a prison, while Henderson admitted robbery and possession of a canister of CS gas found in his home.

Angel, of Rainham Road, Rainham, Essex, received a 51-week prison sentence suspended for 18 months with 100 hours of unpaid work and Patten of Lymington Road, Dagenham, a six-month term suspended for 18 months with a six month curfew between 11pm and 6am, after both admitted money laundering.

Merry, of Cundy Road, Victoria Docks, East London, was earlier jailed for nine months after a jury found him guilty of conspiracy to supply Class B drugs.