Dr Bapel Royburman was released last night after being held prisoner for five hours by the woman, who was armed with a gun, at the surgery in Edmonton, north London. The woman gave herself up to police.
The woman splashed petrol around the surgery before producing a lighter and threatening to set fire to the fuel. Armed police surrounded the surgery, but after four hours of talks Detective Chief Superintendent Peter Kruger, Scotland Yard's most experienced negotiator, persuaded her to release her hostage unharmed.
The woman was demanding a review of the circumstances in which her son died, aged 19, in 1986. She was not happy with the verdict at the inquest into his death.
She arrived at the surgery carrying a petrol can and a firearm, both concealed, at about 1.30pm.
Superintendent Bob Wareing, of Edmonton police, said: 'She was asking for the authorities to review the circumstances of her son's death. The surgery was involved although the actual doctor whom she was holding hostage was not.
'I am very pleased that the siege has been brought to this peaceful conclusion.'
He refused to say how the woman's son died. He added: 'We understand the woman has not recovered from depression.'
Dr Royburman, 57, from Edmonton, looked exhausted as she was led away by police officers. She has been a partner at the surgery for several years.