Robert McWhir, 26, of Potton Road, St Neots, told Cambridge Crown Court today (Monday) that he and Ms Aldrich had been fighting when they fell into a balancing pond at Love's Farm, St Neots, on December 22 last year. McWhir, who denies murder, told the court he has a phobia of water and described how he tried to "clamber over" Ms Aldrich in a bid to get out of the water. Previously the court has been told how on the evening of December 21, McWhir and Ms Aldrich were at a gathering at a flat in Cambridge Road, St Neots. The pair, who had an "on-off relationship" were arguing as Ms Aldrich had been seeing Mcwhir, and her ex boyfriend, Paul Gefford. Today, McWhir told the jury how he and Ms Aldrich had been arguing after leaving the party just before 2am on December 22. He described his relationship with Ms Aldrich as "volatile" and said this was due to her being "feisty" and they argued a lot. McWhir said they were arguing as they left the party and made their way to Ms Aldrich's flat in School Drive and the argument became physical. According to McWhir, the pair wrestled to the floor near the balancing pond, and rolled down the bank into the water, which has been described as between 10cm deep and waist-height. "We were both holding on to each other and fell into the water," he said. "I shat myself, I tried to feel for the bottom. I let go of her and was flapping my arms around. I thought I was going to drown. Eventually, I found Marissa to my right and tried to clamber over her. I was in the water for what felt like just over a minute. Then I felt Luke grab hold of me." Mcwhir then told the court he was angry and he walked off. Previously the court heard from Luke Holder, who said he had telephoned McWhir after he had left the party and McWhir told him 'I'm killing her, I'm killing her'. During cross examination from the prosecution, McWhir denied this and claimed he had said 'this situation is killing me'. Peter Gair QC, for the prosecution, asked McWhir: "Do you accept that Marissa died in relation to this incident?" McWhir answered: "I didn't intend to cause her death." Mr Gair then said: "You must be an innocent man and this was a terrible accident. If it was an accident you wouldn't lie to the police about it." The court heard how when McWhir was arrested he denied knowing Ms Aldrich, but later changed his statement. McWhir had previously pleaded guilty to attempting to pervert the course of justice after he was heard attempting to blame someone else for Marissa's death during a telephone call he made from prison which had been recorded. He also pleaded guilty to breaching a restraining order imposed on him after he broke a window at Ms Aldrich's flat. McWhir will continue to be cross examined by the prosecution tomorrow (Thursday) morning. Ms Aldrich was found face-up in a drainage pond at Love's Farm on December 22. A post-mortem examination revealed she died as the result of drowning.