A transgender Metropolitan police worker accused of attempting to murder her brother has claimed she was in an anxiety and depression-fuelled "mental state" when she attacked him with an iron bar, a court heard today.

Helen Doe, 53, hit her brother Kenneth Doe, 64, several times over the head as he slept in their Mitcham home in Montgomery Close on July 5 last year.

July 7, 2014: Metropolitan Police staff member from Mitcham charged with attempted murder

Feb 10, 2015: Met police worker Helen Doe denies attempting to murder her elder brother

The former Croydon Trans Group campaigner called police in the middle of the night and said: "I've hurt my brother", adding: "I was depressed and suicidal."

Mr Doe, who suffered severe lacerations to his head and a fractured finger during the attack, cried for help as Miss Doe called police from the kitchen clutching the iron bar, a jury at Kingston Crown Court heard today.

Police arrived just before 3am and Mr Doe was taken to St George's Hospital in Tooting.

Miss Doe, who has worked for the Metropolitan Police Uniform Services for 36 years, asked a police officer for a cuddle after she was arrested, the court heard today.

She then told another officer in the van: "I wanted to kill him."

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Helen Doe (left) delivering Easter Eggs to children at King's College Hospital before her arrest last year

Miss Doe, who appeared in court today wearing a black skirt suit and clutching a cuddly toy bunny, was in the process of undergoing a sex change and was taking hormone tablets when she attacked her brother.

She had also recently been prescribed pills for anxiety and depression, the court heard.

She told police officers in an interview after the attack: "I was in a mental state and I didn't know what I was doing. That's why I need to go to a mental place."

The court heard how she told detective constable Kerry Batchelor in a recorded interview the day after the attack that she woke up in the middle of the night and heard voices in her head telling her to "do something".

She told police: "I was tossing and turning, I woke up with a start and I went, 'I have got to kill him' and I went up there because sometimes I think he's going to blow someone's car up and I said I have got to kill him."

She added: "It was only actually when I saw the blood that I realised what I'd done."

The iron bar had been under her bed since the previous summer when her brother allegedly threatened her with a knife, the court heard. Police were called and Mr Doe was cautioned with affray.

Miss Doe also told police that she was unhappy about how her brother talked about murders and killings, especially when they were watching TV programmes, the court heard.

She pleaded not guilty on February 9 to attempting to murder her brother.

The trial continues.