A man accused of murdering a girlfriend has claimed she repeatedly lunged at him with a multi-tool he used for work before he grabbed it and inflicted more than 20 wounds on her neck.

BT engineer Adam Whelehan said he did not know how many times Natalie Jarvis (pictured right) lunged at him before she made contact with the tool.

"It was open and she was coming at me with it," he told a jury of eight men and four women at Maidstone Crown Court. "It caught my hand. I could see the knife was out.

"When she lunged at me, I was scared and didn't know what was going on and shocked."

Whelehan, 23, is on trial alongside Tom Fuller, also 23, who both deny murdering Natalie.

Whelehan, of Roseberry Avenue, Sidcup, admits killing Natalie but claims it was self-defence. Fuller, of Oakley Drive, Eltham, south east London, claims he was not part of a plan to kill Natalie.

Whelehan, who referred to 23-year-old Natalie as JC because he said she looked like comedian James Corden, is alleged to have murdered her because he believed she was pregnant and saw it as the only way out of the relationship.

Natalie was wearing pyjamas, dressing gown and slippers when Whelehan picked her up from her home in Swanley and drove her to Swanley Village, with Fuller hiding in the boot, on the evening of October 3 last year.

Giving evidence, Whelehan claimed Natalie - who worked at a local MacDonald's - had been threatening and blackmailing him over her being pregnant by him.

His memory of the evening of October 3 last year, when Natalie died, he said was "patchy".

Whelehan was out with Fuller and other friends when Natalie contacted him saying she wanted to meet him.

"I said it felt quite dodgy," he said. "I was genuinely quite worried something could happen, because the Saturday before I had received a death threat.

"i don't remember striking her at any stage. i was scared. i was trying to get her off me. i was struggling. i don't know what happened then..." – murder trial defendant adam whelehan

"I feared that if I would go and pick her up there would be people there to attack me, or I would be taken somewhere and they would attack me."

It was arranged for Fuller to be in the boot, he said, because Natalie had been slagging off his father and he would hear what she was saying.

Whelehan said it was his idea that Fuller should hide in the boot.

"My intention was to talk to her," he added. "By this time I had had enough and I was going to break contact."

Whelehan said he had no plans to harm Natalie or the baby she claimed she was carrying. He said he only had sex with her once.

It turned out that she was not pregnant at the time of her death.

"Tom's part would be would be protection in case people were there," he said.

Whelehan drove Natalie to Swanley Village with Fuller in the boot of his Renault Clio, which was not fully closed. The light came on saying it was open.

Natalie, he said, took his multi-tool from the glove compartment. When they reached Button Street, she demanded he stopped because she believed somebody was in the boot, Whelehan claimed.

Police cordon off the spot where Natalie Jarvis died in Swanley Village

He claimed Natalie told him: "If there is someone in the car, I am going to kill you."

"She said it suspiciously," said Whelehan. "She got out of the car. There was no physical contact and no shouting. She went to the boot. She asked me to lift the lid.

"I lifted it slightly and she lunged at me with the multi-tool. I didn't see Mr Fuller in the boot. I imagine she saw him. I didn't see her open the multi-tool.

"She lunged at me and made me go backwards. I managed to grasp hold of the knife. Then there is a struggle. The next thing I know she is on the floor.

"I don't remember striking her at any stage. I was scared. I was trying to get her off me. I was struggling. I don't know what happened then.

"I wasn't thinking clearly. I don't remember chasing her or dragging her into a bush. I remember her falling down a bank and into the road.

"I felt shocked and panicked and my head was in a mess thinking what has happened. Tom was in the driving seat. I didn't give him any instructions to drive the car.

"I remember having the multi-tool and it was in my lap. It was flapping around and there was blood everywhere. I don't remember how many (tools) were open. I believe one.

"I don't remember what happened to it."

Whelehan denied he intended to kill Natalie or cause her any harm. "I was fighting for my life," he added.

The trial continues.