A man accused of beating his heavily pregnant ex-fiancee and their unborn baby to death has described how he became addicted to cheap supermarket alcohol and the Guitar Hero computer game.

Unemployed Tony McLernon told Chelmsford Crown Court that at the time of the alleged killings in June last year, he was drinking more than 20 litres of cider and Lambrini sparkling wine mixed together each day.

He said he would rarely leave his bedroom, instead spending hours on end playing Guitar Hero on the Xbox console.

This "obsession" led to tension in his relationship with his alleged victim, Eystna Blunnie, McLernon said.

"I was very good at the game and was invited to take part in national competitions online," he said.

"But I played it far too much and she began to not like it.

"One night I heard a bang upstairs and went up to find my Guitar Hero guitar had been snapped in half and the only person in the bedroom was Eystna."

McLernon, 24, said his drinking began at the age of 16.

For several years he had met friends in a park near his home in Harlow, Essex. Most nights he would drink up to 12 pints of lager, he said.

As his alcoholism, funded by Jobseeker's Allowance, worsened, he sought out cheaper and stronger drinks.

He said: "A group of us would meet by a bench and drink.

"I would normally have about 12 pints of lager. But in 2012 my drinking changed significantly. I would buy two or three litre bottles of strong cider from the supermarket and mix it with Lambrini to make a drink with 13% alcohol.

"We called it rocket fuel."

McLernon, from North Grove, Harlow, denies murdering Miss Blunnie, 20, and a charge of child destruction by wilfully causing the death of an unborn child.

Opening the case, prosecutor Andrew Jackson told jurors that McLernon had lured Miss Blunnie to her death by sending a text message which read: "I've got a surprise for you."

When she met him in Howard Way near her home in Harlow, he brutally kicked and stamped on her before leaving her fatally injured in a pool of blood, Mr Jackson said.

Miss Blunnie, a catering student and barmaid, was due to give birth to a girl within days.

Miss Blunnie told McLernon she was pregnant with his child in October 2011 but they broke up the following year.

McLernon, who said he had suffered from depression and was prone to self-harm, denied claims he had physically abused her and previous partners.