Tatiana Smurova-Bolton, aged 41, was on the 3.43pm Sunday Southeastern service from Ashford International to St Pancras International when she went into labour.
After coming to a halt at platform 13 shortly after 4pm, the carriage was cleared by staff to give the expectant mother, wife of Henry Bolton, some privacy.
The former Ukip candidate for Police and Crime Commissioner in Kent, who was on the service with his wife and two-year-old daughter Lucinda, said the family’s newest addition, Victoria, was safely delivered by paramedics.
He told the Press Association: “We were travelling up to London as my wife was booked into a hospital there and it became increasingly apparent we weren’t going to make it all the way.”
The delivery was over in a matter of minutes and the family stayed on board while checks were carried out, before being transferred to a nearby hospital by ambulance.