A SEX offender labelled "the nightmare of every mother" by a judge has been jailed for more than three years.

Philip Swift, who was 49 at the time of his offences, posed as a 15-year-old boy called Charlie before beginning to chat with his victim online.

The youngster had been using website InterPals - a site designed for teenagers to meet pen pals from other countries - when she was contacted by Swift.

The defendant had ticked a box stating his age as being 18 or younger when he signed up the site.

Prosecuting, Kerry Maylin told a court there was "intense communication" between the two, who exchanged more than 1,000 texts in a single month.

The girl became aware of Swift's real age and name, but their conversations continued, with the two using video chat site Skype to watch the other performing sex acts upon themselves.

"Mr Swift professed that he loved [the victim] and by Saturday, November 2 2013 various arrangements had been made for him to travel to Bournemouth and stay at the Norfolk Royale Hotel," Ms Maylin said.

The prosecutor said Swift met the girl at a recreation ground before they walked together to the hotel, where the defendant had booked a room using his real name, asking staff for a double bed as he had a bad back.

"He told the girl not to go with him [to the reception desk] and to put a hood and jacket on so she would be disguised," said Ms Maylin.

"He had pre-booked breakfast. The prosecution says this shows a desire to keep the girl out of the gaze of the public."

Once in the hotel room, the two "kissed in a passionate way" before engaging in non-penetrative sexual activity, the prosecutor added.

The relationship was to continue for a year in total before a family member of the victim saw a photograph of Swift on her internet-enabled iPod, and informed her mother.

However, before he was arrested, Swift flew to visit relatives in South Africa, where he remained for six months.

He was arrested at Heathrow upon his return.

In mitigation, Paul Trotman said his client - who suffers from penile cancer - had told the girl of his age "within two hours" of first communicating with her.

The defendant, of Atherley Road in Shanklin, Isle of Wight, admitted meeting a child following sexual grooming and two of sexual activity with a child.

On Friday, Judge John Harrow, sitting at Bournemouth Crown Court, sentenced Swift to three years and four months behind bars.

He said: "You must represent the nightmare of every mother of a teenage girl.

"You are 50 now, and were 49 at the time. You employed quite a degree of subterfuge and craftiness to establish contact with this young girl on an innocent internet site."

Swift will be subject to an indefinite Sexual Harm Prevention Order upon his release.