A transgender Metropolitan police worker who battered her brother over the head with an 18-inch pole has been cleared of attempted murder after her sleepwalking defence was accepted by the jury.

Helen Doe, 53, was charged last summer after attacking her brother Kenneth Doe, 64, in their Mitcham home on July 5.

But a jury at Kingston Crown Court yesterday accepted her defence that she did not intend to kill him.

Mr Doe suffered three severe lacerations to his head during the attack as he lay in his bed in Montgomery Close.

Helen Doe told police that as soon as she saw the blood and realised what she had done, she called 999 for help.

After her arrest, she asked an officer: "Can I have a cuddle?"

Confused about what had happened, she later said to another police officer: "I don't want to hurt anyone. I wanted to do it. I wanted to kill him."

Miss Doe had worked for the Metropolitan Police Uniform Services for 36 years. She was a member of the Croydon Trans Group and was in the process of undergoing a sex change via hormone tablets.

The court heard how she was prescribed a combination of anxiety drug propanolol and depression drug duloxetene by her GP three weeks before the attack.

Four expert pharmacologists who gave evidence at the trial agreed that the drugs combination could have caused her violent behaviour.

Defense barrister John Hilton claimed she was acting under "non-insane automatism" - involuntary reflex movements caused by her medication - when she throttled her brother.

Under criminal law, if this defence is proven, a defendant cannot be found liable for their actions.