Traders and townspeople in Marlborough were shocked this week when Wales and West Utilities brought in a one-way system in the town centre as they replaced a gas main.

Although the town council was notified in June that work would take place during the summer, it was not until last Thursday that signs went up in Herd Street warning of the diversion. Details appear on a small notice attached to a lamppost at the corner of Herd Street and Silverless Street.

Traffic is one-way down Herd Street and Barn Street, while the work on the new gas main takes place at the junction of Oxford Street and The Green. Vehicles that would normally drive up Barn Street have been diverted up Kingsbury Street, which is also one way.

But there was chaos on Monday morning when drivers, unaware of the diversion, continued to drive down Kingsbury Street and turn into Silverless Street, despite “no entry” signs.

Sue Rumbold, owner of the Cat’s Whiskers shop at the foot of Kingsbury Street, pictured left, said her business has been hit. “It has been completely mismanaged,” she said. “No one knew anything about it until it all started at rush hour on Monday.

“Now all the heavy lorries are negotiating the tight bend at Kingsbury Street right outside our shop. It is terrifying. You just wonder if they’re going to make it.”

Mrs Rumbold is concerned for the safety of pedestrians and, at her insistence, Wales and West Utilities has erected signs warning of walkers, but the constant traffic continues to make crossing Kingsbury Street hazardous.

A spokesman said: “Advance warning of the works was given and signs went up several days before the work was due to commence. We have received some complaints but on the whole the diversion is working well.”

The work is due to continue for up to three weeks but will continue through the town, causing more disruption.

There was concern that the contractors would move on to George Lane later in the summer but Wales and West Utilities said the scheme was still out to consultation and was not likely to take place until early in 2010.

Meanwhile, residents have been told by Wiltshire Council that work on Pewsey Road Bridge is unlikely to begin until next summer, avoiding the Jazz Festival and Mop Fair.