A 55-year-old man from High Wycombe accused of trying to meet an underage girl for sex told a jury today that he knew he was being set up.

The prosecution allege Mark Porter - who was 54 at the time -  travelled from his flat in High Wycombe to Luton train station where he was expecting to meet a 14-year-old virgin called Jenny, who he groomed over the Internet and in phone calls.

But a jury at Luton crown court was told he was caught in a sting set up by paedophile hunters Neil and Katie Ivall, from Dunstable.

In the witness box Mr Porter said: "It was a hoax - a set up. I was just playing along with a stupid game. I knew it was a set up from the beginning."

He said he went along with 'the hoax' to find out who was behind it, believing it to be a man he knew.

Mark Porter, of High Wycombe, denies attempting to meet a child following sexual grooming.

The defendant denied the allegation, from prosecutor Will Noble that he was trying to “claim” Jenny’s virginity saying he simply drove to Luton to confront the people behind the hoax.

Mr Noble asked him why he had told 'Jenny' he had sex with another 14-year-old, saying: "There is no way you would have said to them (the paedophile hunters) that you have previously had sex with a 14 year old girl."

Mr Porter replied: "That's what they wanted to hear."

Questioned why he sent her a picture of his bed, he said: "She asked me to send pictures."

He was asked why he had sent her a picture of his fridge full of fizzy drinks and sweets, he replied: "I am a diabetic, and later went on to claim he was just “playing a stupid game.”

The defendant told the jury his GP had prescribed Viagra because he had been suffering from erectile dysfunction, but he said it did not work.

Earlier the prosecutor told the court the Ivalls run a non-profit organisation called 'Chris Fear' after a member of Katie's family was groomed over the Internet by a paedophile.

He said Katie had been contacted by a man who claimed his 11-year-old daughter had been contacted by Mr Porter over the Internet.

As a result, she set up a fake Facebook account using the name Jenny Johnson and posted pictures, saying she was 14 years old.

Porter allegedly repeatedly send flattering messages to Jenny, promised gifts and treats and asked for pictures of her.

The case continues.