It was designed to withstand once in 100 year floods - but two years after Yarm's £2.1m flood defence scheme was opened it was realised the walls had not been built high enough.

The floods of 1995 turned Yarm High Street into a canal with water up to 18 inches deep. After running out of sand - 40 tons of it, shovelled into 1,500 bags - Stockton Council provided anxious residents with ramparts made from 500 bags of rock salt.

Now a further £2m has been spent on building up the defence walls.

The Environment Agency says the original scheme completed in 1993, protected the town from flooding several times.

It says knowledge gained following the 1995 flood showed that the original height of the floodwalls gave a lower than desirable standard of protection.

The upgrade has given the walls another half metre in height.

Jo Turnbull, chairwoman of the Northumbria Regional Flood Defence Committee, said: "This improved scheme is a major step forward to providing better flood protection for residents and businesses in Yarm.

"Although we can never prevent flooding, the work will reduce the frequency of flooding and members of my committee recognised the need by agreeing to help fund the project.''

Construction work on the original scheme, opened by the town's then Tory MP, Tim Devlin, was not helped by a sub contractor going bust.

The hydraulic modelled defences had been designed to withstand severe floods which return every 100 years. The floods which occurred in 1995 - just two years after the scheme was completed - were said to happen only every 50 years.

Looped by the River Tees, Yarm has always been prone to flooding. In the great floods of 1881 boats were actually rowed up and down the High Street.