Baby Nikol weighed 2.95kg (6.4lbs)
A police officer who planned to have a stern word with a driver who overtook him ended up helping deliver his baby.
Pc Dan Wells was driving in south-west London when Michael Nadel, 39, flagged him down asking for help to get to The Portland Hospital in central London.
Pc Wells called an ambulance but Mr Nadel, from Surrey, told him his wife's labour was moving faster than expected.
"I didn't know what to do but I told the mum to push and out came the baby," said Pc Wells.
Pc Wells said: "He [Mr Nadel] was behind us and overtook then pulled in. I was about to have words with him about the way he was driving then he said his wife [Natalia] was having a baby."
"I think he was hoping for a blue light escort but instead we decided to call an ambulance."
Pc Wells and his colleague Pc Felicity Cullen saw the baby was on its way when they went over to the Russian couple's grey BMW which was parked on Fulham Road.
"The head was out and it was kind of blue. We could see the umbilical cord wrapped around the baby's neck," Pc Wells said.
"The baby hadn't made a noise at that time so we wondered what we were dealing with."
Mr Nadel, a banker from Walton-on-Thames, in Surrey, praised Pc Wells for his quick-thinking.
"Nikol weighed 2.95kg (6.4lbs) and is doing well," he said. "It was very dramatic.
"I'd like to say thanks to him. The policeman really helped us.
"It was fantastic. I'm very, very happy."
The police officers were on their way back to Fulham police station to file some paperwork when the baby girl arrived at 0325 BST on Thursday.
Pc Wells, who has no children of his own and has had no training in delivering babies, said: "I just did what I thought at the time was right."