A man who wired an explosive device to his wife's car on Christmas Eve after starting an affair with a woman he met on the internet was jailed for 10 years yesterday.

Robert Bottom, 36, told his wife, Caroline, he was fitting a hands-free mobile phone in her Peugeot car, parked at their home in Chattenden, Rochester, last year, Maidstone Crown Court was told. Later that night, Mrs Bottom, who works as a carer for the elderly, was driving home from a visit when there was an "almighty explosion".

The car was severely damaged but Mrs Bottom walked away with only minor injuries.

Bottom, an engineer, of Hawkinge, Kent, pleaded guilty to causing an explosion likely to endanger life or cause serious injury to property.

A second charge, of attempted murder, was left on file. For the defence, Sunil Rupasinha said Bottom had not foreseen the degree of force generated by the theatrical maroon, used to simulate rifle or cannon fire, that he placed under the driver's seat.

Mrs Bottom had suffered only minor injuries, although he accepted they could have been much more serious.

He added that, because of the case, Bottom would lose his £200,000 home as well as his engineering business. He had done it "to give a shock to his wife" at a time of stress in the marriage.

Jailing Bottom for 10 years, Judge Patience told him the sentence was heavy to act as a deterrent to an offence of the "utmost gravity".

Robin Johnson, for the prosecution, told the court the couple met in 1994 and married four years before the incident. But Bottom met a woman on the internet through a shared interest in caravanning and started an affair with her.