Foundations of an Iron Age round house have been discovered in Levington during a £30million scheme to boost power supplies in south Suffolk and north Essex.

UK Power Networks is laying two underground electricity cables and removing overhead lines as part of the project covering power supplies to Felixstowe, Shotley and Harwich.

As part of phase one 21km of overhead lines have been taken down around the the Area of Outstanding Natural Beauty and Special Protection Areas along the rivers and coastline, two circuits of 16km of 132,000-volt cable laid between Ipswich and Felixstowe, and two circuits of 10.5km of 33,000-volt cable laid between Nacton and Felixstowe.

A second phase, due to start in mid-2017, will see drilling under the rivers Orwell and Stour of a total distance of 2.8km to link the peninsulas together and 12km of 33,000-volt cable laid between Felixstowe, Shotley and Harwich.

Chris Sugars, project manager, said: “As large swathes of the land adjoining the rivers is of historic and natural importance, we have liaised with numerous organisations.

“The final archaeological investigations are now being carried out, ahead of the project starting in earnest, to safeguard any possible ancient artefacts which are preserved in the ground.

“The archaeologists have so far found the foundations of an Iron Age round house and will continue to uncover and record any sites of interest along a 9km stretch of farm land before the trenches are dug for the cables.”

Abby Antrobus, Suffolk County Council’s senior archaeological officer, said: “We have been pleased to work with UK Power Networks and Albion Archaeology to design the programme to record sites of interest along the route.

“The project gives a transect through the archaeological landscape along the Felixstowe Peninsula, investigating prehistoric, Roman and Medieval sites that have been identified through cropmarks and the systematic evaluation trenching.”

The entire project will be completed by the end of 2018.

Mr Sugars added: “The project is very challenging. We are working closely with councils regarding all the work. While there will be some traffic disruption in both Shotley and Dovercourt during the second phase of the project, we aim to keep this to a minimum and it is for a long term benefit to about 45,000 customers.”