Tam Dalyell: Tireless campaigner

Mr Dalyell, who has previously raised the problem in the Westminster parliament, said he had seen for himself the deterioration of the structure.

He said: "I have been given a tour of the bridge and the problem is, that dirt that gets into nooks and crannies, creating decay."

"In addition, little holes have been drilled in the structure, for the lights illuminating it, and that is where rust starts."

The MP fears that delays caused by the Railtrack hiatus, will lead to further rusting and make future repairs more costly.

World heritage site

Railtrack said it was designing a maintenance plan for the bridge, with contractors Balfour Beattie.

But bridge preservation campaigners will be looking to ensure that the organisation which takes over from Railtrack, will actually implement that plan.

Meanwhile, it seems that a hoped for boost for the preservation of the bridge may be too far in the future, to put pressure on the Government to act.

The structure is waiting in the wings, on a list of sites to be granted World Heritage Status.

One of the engineering wonders of the world

However, the recent designation of New Lanark as a World Heritage site, may be the last for some time to come, north of the border.

The bridge was placed on Unesco's 'tentative' list, by the British Government, in 1999 alongside New Lanark and 23 other UK locations

But Unesco (United Nations Educational, Scientific and Cultural Organisation) has decided to limit the number of sites any country can nominate, to one a year from 2002, so the bridge may have to wait a while.

Built in the 1880's by Benjamin Baker, the structure has long been regarded as one of the engineering wonders of the world.

Engineering feat

The revolutionary cantilever design at first shocked the Victorians, still nervous after the Tay Bridge collapse.

But eventually the bridge came to be a source of national pride.

At the height of construction 4,500 workers from a dozen countries worked to build it.

It was the first cantilever bridge and the first large steel bridge.

The selection of the bridge for tentative inclusion as a world heritage site marks a shift away from cathedrals and medieval cities, towards natural and industrial sites, by the Unesco heritage panel.