To the untrained eye, it looks like any other electric unit providing commuter services on Essex rail lines – but there is a clue that there is more to this train with its label: “Batteries included.”

Because the train that has been in service on the line between Harwich and Manningtree for the last five weeks could eventually revolutionise services on branch lines across the country.

It is an electric train, picking up power from overhead lines, but it also has battery motors allowing it to run on non-electrified lines.

At present the battery range is officially 50 kilometres, but this could be expanded with addition of new batteries and changes to its electrics.

This could allow it to run from London to Lowestoft, using overhead power as far as Ipswich and then using battery power for the rest of the journey.

The battery train was adapted from one of Greater Anglia’s Stansted Express units, and will return to west Anglia next month after it has been converted back to a standard electric unit.

But its success in Essex could prompt a new generation of electric/battery hybrids to be built – the existing diesel units used on non-electrified are getting old and there are no replacements in the pipeline.

The hybrids could allow through trains to return from the east coast stations to Liverpool Street – although at the unit’s launch yesterday it was pointed out that there is limited space on the main line and short trains from the East Suffolk line might not be practical.

Terry McCarthy from Network Rail said: “In theory it is true that these trains could run from branch lines to London, it is one of the possibilities that will be evaluated after these trials.”