Both mum and baby are doing well after PC Robert Morgan helped with the delivery after being flagged down in the middle of his shift.
The new baby girl doesn't have a name yet but she's happy and healthy.
More top news
Two police officers helping to guard diplomats have been sacked for sharing pornographic images on their mobile phones.
A 32-year old man from Hampton has been jailed for five years historic sexual assaults in the late 1990s.
A teenager who was mistakenly released from prison after he was arrested on suspicion of attempted murder has been detained by police.