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
An armed robber who targeted fast food shops in north west London has been jailed for eight years.
Police have arrested a number of cannabis dealers in Haringey as officers targeted a hotspot for street drug dealing.
A thief who posed as a council worker snatched cash from an 86-year-old woman's pension book, the Met Police said.