Ken Wenman, the boss of the new, enlarged ambulance service serving Wiltshire, believes it will lead to improved performance for patients.

Great Western Ambulance Service (GWAS) merged with South Western Ambulance Service Foundation Trust today.

The new ambulance service, called South Western, will serve a resident population of more than 5.3 million plus an estimated annual influx of 17.5 million tourists.

It covers Wiltshire, Avon, Gloucestershire, Somerset, Dorset, Devon, Cornwall and the Isles of Scilly. The head office is in Exeter.

The merger has taken 14 months to conclude and Mr Wenman said in that time performance at GWAS had improved.

Mr Wenman, chief executive of South Western, said: “Since South Western has been working with GWAS we have moved from GWAS being one of the poorest performing ambulance trusts to last week being the best ambulance trust in the country on response times for Category A8 (life threatening) calls. We have spent a lot of time looking at how we deploy our ambulance resources and sending the right resources to incidents.”

The service employs about 4,000 people and Mr Wenman said all staff from GWAS had transferred under their same terms and conditions.

He said the jobs of clinical front line staff were protected but there would be a reduction of about 20 posts in administration and management. Consultation with affected staff has started and will take five months.

Jenner House, on Langley Industrial Estate, Chippenham, which is the headquarters of GWAS, will close in December and staff relocated to other offices.

He said there were no plans to close ambulance stations and in fact a new ambulance station will be built to replace the existing one at Malmesbury Road, Chippenham.

Mr Wenman said the benefits of merging the two ambulance services included economies of scale to obtain better value in buying medical equipment and ambulances. As a Foundation Trust, South Western will be able to use surplus money to reinvest in services.

The new ambulance service will have to make efficiency savings ordered by the Department of Health of £10 million a year.

The Wiltshire emergency control room based at Wiltshire Police’s headquarters in Devizes will close in March saving £700,000 a year and 999 calls will be answered at its control room at Bristol.

Although the GWAS name will disappear Mr Wenman said the only replacement signage will be at the 34 ambulance stations in the GWAS area, which will cost £4,500.

He said changing the name on ambulances and other things would not take place for several years as the total cost of replacing the name would be £260,000.

Jo Fowles, secretary of the GWAS branch of Unison, said the union cautiously supported the merger.

She said: “For the majority of staff such as ambulance crews and paramedics it’s business as usual and we expect members of the public will see very little difference from the service. However, it is a period of uncertainty for many staff, particularly those who work in back office functions who will be worried if their jobs are at risk.”