A mother accused of murdering her three-month-old daughter insisted on swapping phones with her sister while the baby was being treated in the back of an ambulance, a court has heard.

Paramedic Anthony Steadman told how Rosalin Baker, 25, appeared to show no reaction as he and his colleagues tried to save little Imani Wiltshire’s life.

He said: “She wanted to swap her mobile phone with her sister.

“She wasn’t prepared to leave until she had done that.

“In 18 years in the ambulance service, and 16 years on the front line, I have never seen that reaction from a parent before.”

The Old Bailey heard this morning how Baker’s sister had arrived in High Road, Stratford, shortly after the number 25 bus had stopped close to the junction with Carpenters Road on September 28 last year.

Jurors heard how medics were called to the scene to reports of Imani not breathing on board the bus, with rapid response driver Lyndon Ashurst was the first to arrive at 10.11am – three minutes after he got the message to attend.

He said: “There were two buses at the bus stop and my eyes were drawn to the second of the two buses as there was a large group of people standing by the back of the bus.”

He told how Imani was lying on top of a coat on the floor of the bus, with a passenger giving her CPR.

Baker, he said, was sitting “in the foetal position” and that he identified her as Imani’s mother by the sling she had on.

Asking her what happened, Mr Ashurst, who has worked for the London Ambulance Service since 2009, said: “She said that the baby had been crying 10 minutes earlier.”

Mr Steadman testified that Imani’s coldness – 10 degrees colder than normal body temperature – did not seem to match up with that.

Mr Ashurst said that blueness around her eyes were a sign that she may have had an injury to the bottom of her skull.

Baker and her partner Jeffrey Wiltshire, 52, of Morris Avenue, Manor Park, deny murder and causing or allowing the death of a child.

The trial continues.