A prison officer who had an intimate relationship with a jailed diamond robber and sent him videos of herself performing a solo sex act has been jailed for eight months.

Abbie Levens, 32, has admitted having an improper relationship with criminal Sherome Blair while she was working at HMP High Down and he was serving a sentence there in 2011 but denied it was sexual.

But, following a trial of issue being held at Guildford Crown Court ahead of her sentencing , judge Peter Moss today said the nature of their relationship - whether it was physical or based on explicit texts and fantasies - undermined the judicial system.

Judge Moss criticised Levens, of Adastra Way, Wallington, for knowing Blair had mobile phones in prison and not only not reporting it to her fellow officers, but indulging in the exchange of sexual messages.

He said he could not be sure they did have any physical sexual relationship but said the nature of their correspondence meant it would have been "beyond the endurance of human nature to resist a stolen kiss or cuddle" if they had the chance.

He jailed her for eight months and said: "You accept that you did have contact with him, by mobile phone and in writing including sending him obscene, sexually explicit material - in particular a video of you masturbating.

"You can't deny and don't deny that you failed to report the fact that he had mobile phones.

"You embarked on a wholly and utterly inappropriate relationship given your positions in the prison service.

"Possession of a phone is a very serious breach of the integrity of the prison system.

"He was suspected of involvement with very serious crime. For such an individual to access a phone undermines the prison system."

Levens cried and mouthed "bye mum" to her mother in the public gallery as she was led to the cells.

Levens met Blair when she was a guard at Highdown prison in 2011. Blair had been released on license after serving part of a sentence for a diamond robbery but had been recalled after being arrested on suspicion of kidnap.

Their relationship started with a single letter passed from Blair to Levens but quickly escalated to sending each other explicit messages and regular phone calls.

Levens claimed letters detailing illicit encounters in the prison were "stories and fantasies".

Judge Moss gave Levens a reduction in the initial two year sentence he considered on the grounds she had suffered distress prior to the relationship owing to her involvement in a trial against guards at Downview prison where she used to work.

Levens gave evidence for the prosecution, in a trial where it was alleged guards had had sex with inmates at the women's prison..

It resulted in her being transferred to Highdown and Judge Moss conceded she was vulnerable when she met Blair.

But he dismissed calls for her sentence to be suspended on the grounds it would send the message that officers would not be liable to be jailed for helping prisoners.

Levens had apreviously admitted a charge of misconduct in public office.