Giff, who has served for 15 years, remains a police officer pending disciplinary proceedings.

BBC: Diplomatic protection officer jailed for sex on duty

Married Giff, of Sandy, Bedfordshire, admitted three counts of misconduct in a public office.

BBC: Diplomatic protection officer jailed for sex on duty

Richard Atchley, representing Giff who has two young children, said he apologised for his actions, especially to his wife and colleagues.

BBC: Diplomatic protection officer jailed for sex on duty

Ricci Giff, 38, an officer with SO6, whose job included guarding Downing Street, disappeared while on duty on three occasions, in late 2011.

BBC: Diplomatic protection officer jailed for sex on duty

He said: "He has paid a high price for his foolish and unprofessional behaviour, " he added, saying Giff never missed a check during his motorcycle patrol in the capital.

BBC: Diplomatic protection officer jailed for sex on duty

Judge Anthony Pitts told Giff that what he did during their meetings was not important, but the fact he was unable to respond if there had been an emergency was.

BBC: Diplomatic protection officer jailed for sex on duty

The court heard Giff met Ms Ramsden on other occasions, including one December 2011 shift when he was on duty outside Downing Street but on a legitimate break from his 12-hour shift.

BBC: Diplomatic protection officer jailed for sex on duty