The family of a great-grandmother killed by a wheel that fell off a trailer are calling for a change in the law for the upkeep of farm vehicles.

Doris Smith's family want the law - which says farm vehicles travelling below 20mph on public roads do not need annual inspections, to be re- viewed.

Mrs Smith, 84, died after the wheel and hub flew off the trailer and struck her as she was walking along Ashingdon Road, Rochford, on July 11, 2005.

Farmers Howard Baker, 55, of Marsh Road, Tillingham, and Martin Baker, 53, of Lower Road, Hockley, were cleared last week of manslaughter after a two-week trial.

The brothers admitted they did not have a full inspection of the trailer when they bought it or carry out checks of the wheel assembly, but the court was told this was not illegal.

Mrs Smith's daughter, Linda Copsey, said: "The case has highlighted the responsibility farmers must take in maintaining their vehicles, especially if they are to be used on the public highway.

"It is essential further regulation is introduced to ensure agricultural vehicles are maintained for everybody's safety.

"We would not have lost our lovely mum in such a terrible way if there had been such legislation in place."

Mrs Copsey, 48, from Rayleigh, who thanked Essex Police for their help in the past 18 months, added: "We are going to try and do something on this because I think it is clear that if it is a vehicle on the road it should be maintained."

Mark Francois, MP for Rayleigh, has spoken with Mrs Smith's family previously about the issue and written to the transport minister about how the law operates.

He said: "I recall dealing with this case, which I know has been a tragedy for the family involved.

"If they would like to come and see me at my constituency surgery, we can talk this through to see if there is anything further that may be done."

But he admitted: "Changing the law in this respect is not easy."

No one at the Department for Transport was available for comment.