Rebecca Casterton and Lauren Brooks died in the crash in January

Robert Murray, 51, of Wrockwardine Wood, Telford, is charged with causing death by dangerous driving.

He told a jury how he felt a bump, then saw in his mirror the underside of a Renault Clio as it landed upright.

Rebecca Casterton, 13, and Lauren Brooks, 12, died on the A38 in Clay Mills in Staffordshire last January.

The 51-year-old father told Stafford Crown Court that he had earlier made a call to his wife on his hands-free telephone, but was watching where he was going.

'Checked mirror'

He said before moving into the offside lane, he checked his rear view mirror, indicated, looked again and, still straddling the white lines, felt a judder.

Mr Murray said: "I was devastated. I thought it was a safe manoeuvre.

"I was not on a mobile phone at any stage when I was overtaking."

The prosecution said the Clio was spun out of control into the central reservation and landed upside down in the opposite carriageway where it was hit by a Mercedes car.

In a statement to the jury, Mrs Irene Corrie, Lauren's mother, who was driving the Clio, said she was aware of Murray's lorry coming alongside her.

"Then it seemed to go backwards and I then felt a bang at the back of my car. I knew the lorry had hit us."