A charge of speeding against an ambulance driver who was delivering a liver for a transplant patient has been dropped, it was revealed today.

Mike Ferguson, from West Yorkshire, was due to appear in court next week after being charged with speeding earlier this year. He was stopped by police as he drove down the A1 in Lincolnshire in January delivering a donor liver from St James's hospital in Leeds to Addenbrooke's hospital in Cambridge when the incident happened.

Mr Ferguson's union, the GMB, revealed today that the crown prosecution service had decided that the prosecution was not in the public interest. The had been due to be heard at Grantham magistrates' court on Monday.

Mr Ferguson, 56, who faced losing his job if he had been prosecuted. said he was "overjoyed" at the news. He said: "I am ecstatic, but the fight does not stop here. I am going to continue campaigning to clarify the law so that other emergency service drivers don't have to suffer the same experience.

The last few months had been "hard work", Mr Ferguson said, but the support of the public had helped him to continue. "As far as I was concerned I was in the right. When people are waiting for transplant organs it is essential that they receive them as quickly as possible. This case was an emergency as far as I was concerned."

John Durkin, the GMB's branch secretary for ambulance drivers, said he was "over the moon" that the case had been dropped. "We can now get back to the business of saving lives. If Mike had been found guilty, the repercussions throughout the service would have been very damaging.

"We are all trained to drive safely at high speed and we take our jobs very seriously. A few minutes make a big difference when you are in the business of saving lives."

Earlier this week, Mr Ferguson travelled to Downing Street to hand in a petition signed by more than 18,000 people supporting his case. Mr Ferguson has an unblemished employment record stretching back 36 years and has a clean driving licence.

Operations director for West Yorkshire metropolitan ambulance service, Bob Williams said: "We are pleased that Mike Ferguson will now be able to continue his work without the threat of a court case hanging over him. We look forward to being able to continue to work as part of the UK human organ transportation programme."

Ken Williams, a trustee of the RoadPeace charity that campaigns on behalf of road crash victims, commended the work of the emergency services but added a cautionary note. "They are doing a great job but we are only too aware as a charity of the deaths and injuries caused by the emergency services," he said.

"The public have given the police a lot of criticism over this case because of the perception that the delivery of every organ is an emergency, but this is not always so. I think the authority to drive at speed in each case should be checked.