The jury at Nottingham Crown Court listened to transcripts of police interviews with John Height, who denies his part in 52-year-old Mrs Anderson's murder.

Mrs Anderson was battered with a saucepan and hammer before being driven to a bank of the River Welland, near Crowland, where she was repeatedly stabbed and dumped in the water.

She was murdered on the day she bought herself a dress in anticipation of accompanying her husband, Malcolm (54), to an office Christmas party last December.

She had no idea he had pledged his future to colleague Claire Jackson.

Miss Jackson fell in love with Anderson after he became her boss at the Norfolkline haulage company in Whittlesey.

He was so desperate to be with the 26-year-old that he allegedly plotted with workmate Height (38) to "get rid" of his wife.

It is claimed Height agreed to help murder Mrs Anderson in return for £20,000 – and that she was driven to her death in his Mercedes van.

Anderson, of The Mill, Kirton, Lincolnshire, has admitted murdering her last December, but Height, of Driffield Way, Woodston, Peterborough, denies the charge.

Yesterday, the jury heard that Height later told police how, on December 8, last year, Anderson had asked to borrow his silver Mercedes Sprint van.

He agreed and the pair met up in a layby.

Height said he stayed in his van seat while Anderson got out of his Peugeot car and then "felt the van rock" as Anderson put something in its back.

Height followed Anderson to Crowland where both vehicles stopped by the river.

Height heard Anderson open the van doors, and 30 seconds later was startled when his Peugeot burst into flames.

He told police he thought Anderson had torched the car in order to make an insurance claim.

Height told police it wasn't until the following Monday afternoon at work he noticed blood in the back of his van.

By then it was common knowledge that Anderson had been arrested on suspicion of murdering his wife, and a workmate of Height, who had also spotted the blood in the van, alerted police.

Detective Constable Diane Squires told the court that when an officer arrived at Height's workplace, he immediately volunteered information.

He came forward and said: "I have to tell you I think I've got involved in something I didn't do."

Height, who has no previous convictions, was then arrested on suspicion of assisting an offender.

Timothy Barnes QC, defending, told the jury: "In effect, he (Height) was saying 'I've been used. I didn't know what was going on'."

The trial continues.