The reason a mother, driving with her young son, suddenly pulled out in front of a delivery lorry will never be known, the inquest into her death has concluded.

Jessica Winterborn, of Millers Green, Harleston, died the day after the accident, at the junction of the A140 and the B1077 at Brome, near Diss, on November 27 last year.

Her son Harry was not hurt. The 24-year-old had been due to marry her fiancee very shortly.

Antony Potts, who was driving the Tesco Mercedes LGV south-bound on the A140, told an inquest at Norfolk Coroner’s Court he was driving below the 40mph speed limit and had his lights on because it was overcast and had been raining.

He said he noticed a red car stop at the junction but it suddenly pulled out just as he reached it and he had “absolutely no chance” of avoiding it.

Christopher Earl, who was behind Miss Winterborn, said: “I can say without any doubt that the Tesco lorry was going well within the speed limit. It was not going very fast.”

PC Richard Godden said reasons for the car pulling out could have included the driver failing to see the lorry, misjudging its speed, being momentarily distracted or thinking the lorry was going to turn, but he could not be sure.

Coroner William Armstrong said Miss Winterborn was normally a safe and responsible driver.

He told Mr Potts there was nothing he could have done, and recorded a verdict that Miss Winterborn died as a result of a road traffic collision.