Greater Anglia is set to introduce the first of its fleet of new suburban electric trains on routes in Essex within the next few weeks – but they are unlikely to be seen in the Ipswich or Colchester area until the New Year.

The British-built Bombardier Aventra trains have been on test around the region’s electrified lines since the spring – and have been seen on Belstead Bank and at Ipswich station.

MORE: Greater Anglia starts testing Aventra trains

But they will be first introduced on the line between London Liverpool Street and Southend Victoria via Shenfield. Greater Anglia is planning a “soft launch” on this route and the branch line to Burnham on Crouch and Southminster.

They are expected to then run to Braintree and on local services to Colchester before they then take over services on all electric routes in the east of the region – to Ipswich, Harwich, Clacton, and Walton.

The new trains are expected to be introduced on West Anglia lines – from Liverpool Street to Cambridge – from later next year and into 2022.

A spokeswoman for Greater Anglia said the trains would be introduced into one area of the network first before being put into service in other areas – but she was confident they would be welcomed by passengers.

She said: “They are very smooth, the seats are very carefully designed to be comfortable and they are very open and airy – they also have very good acceleration and should speed up services.”

The company was not planning to hold a major launch at this stage – but she said passengers would certainly notice the new trains when they did come into service.

The Aventra trains are mostly in five-carriage formations although some are 10-carriages long and will make up the bulk of Greater Anglia’s fleet for many years ahead. They are standard-class only and all seats have access to power points and USB sockets. They have wifi throughout.

MORE: What are the new Aventra trains like?

The Aventra family of trains are being built by Bombardier at its Derby factory – and other rail companies across the country including Transport for London, London Overground, West Midlands Trains and South Western Railway have also taken large numbers of the trains which are likely to remain in service until the middle of the century.