An overheard pub conversation led the embarrassing sale of two big screens for �16,000, bought nine years ago for nearly �600,000, to be exposed.

The revelation came as opposition councillors grilled Charles Reynolds, Great Yarmouth's cabinet member for tourism, over the circumstances of sale at last night's scrutiny meeting.

It emerged that the screens were so prone to error that engineers stood by when World Cup football matches were shown so 'there would not be too many dissatisfied residents' if anything went wrong.

And borough council leader Steve Ames said ADI - the company that sold the authority three screens for nearly �900,000 - had so little faith in the screens that it was not prepared to tender for an annual maintenance contract at 'a reasonable annual price' just four years after the screens were bought.

Trevor Wainwright, Labour councillor for Magdalen ward, had asked whether screens could be moved to the market place to show the Olympics at an earlier cabinet meeting. He was told that the Conservative group would look into it, but days later he found this was not the full story.

'A Labour councillor heard in the pub that they were being sold,' said Mr Wainwright. 'We weren't told.'

He said he was sceptical that the matter was kept quiet weeks before the borough's May elections, which see council leader Steve Ames and tourism cabinet member Charles Reynolds put to the public vote.

And he asked whether the council had sought better value for the two screens than the �16,000 it received.

Mr Reynolds defended the sale, stating he approached other organisations but only had one other expression of interest that did not come to fruition.

'I was told the only good thing about the screens is the shells,' added Mr Reynolds. 'The technology is dead and buried.'

And he said he was not more open about the sale as 'this would not be politics if we told the Labour party everything.'

The council decided to sell the screens, which cost �300,000 each, after being told it would cost �200,000 to refurbish them. Council leader Steve Ames said: 'I'm proud we made that decision before the elections, to draw a line under it.'

A third screen, which broke down only two years after being installed in the Market Place, was written off after a protracted but fruitless legal battle with the manufacturer.