Contractors working at the site in the heart of Preston city centre have been digging dozens of bore holes to hunt for archaeological remains and find out the geology of the area.

Holes have been drilled using specialist equipment on Lancaster Road, Percy Street, Tithebarn Street and around the bus station and market hall.

Developers at the site need to know exactly what is underground to enable them to dig out and make the foundations for the scheme correctly and safely.

A Preston Council spokesman said: "The digging has been going on for several weeks all around the Tithebarn area.

"This is important for the builders as they need to know if the ground is rock or sand so they know how big the foundations need to be. Digging is now very much on the wane."

The county council's archaeology department has also insisted the samples are checked for historic remains as part of the pre-application process.

This will allow any extra time to be incorporated into the work if a full survey needs to be carried out and planners have stressed this is routine in major applications.

A planning application for the scheme – which includes a new John Lewis department store, shops, leisure facilities, and housing – is due to be submitted at the end of the year.

The Evening Post reported how development works were delayed on halls of residence in Marsh Lane when 30 graves from a medieval friary were discovered by builders.

But significant finds are not expected around the Tithebarn site as much of the area was redeveloped in the 1960s when the Guild Hall, market hall and bus station were built.

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