SIR - What is so sad for Bradford, at one time known as the Florence of the North, is that stone cleaning arrived too late to save many of its great buildings.

In the picture of the Kirkgate entrance to Kirkgate Market, left, can be seen how black Bradford was, with more than a century of soot having settled on the city from mill chimneys.

Some of the proprietors of the Market had the Darley Street entrance cleaned with the new technology to demonstrate to councillors just what the building could look like cleaned but, sadly, to no avail.

The market was knocked down to make way for the Kirkgate Centre, the site being the most valuable new development site in Britain at the time such was the standing of Bradford then.

It must be said that as the decline in executive shops and the disappearance of famous department stores has taken place, the Kirkgate Centre remains at the heart of the Bradford shopping experience today.

Iain Morris, Caroline Street, Saltaire