THE centrepiece of the fascinating exhibition based on the recently-rediscovered diaries of 19th-century Blackburn printer and alderman Charles Tiplady who chronicled life in the town during the most important period of its growth, an enormous painting of the laying of the foundation stone of the town's Cotton Exchange in 1863 is also one of the town's greatest historical treasures.

Indeed, following the ending last month of the Tiplady exhibition, which featured Blackburn's sometimes turbulent transition from little more than a village to the factory-filled weaving centre of the world, the picture is to remain on prominent display at the Museum and Art Gallery.

It was done by the Russian artist Vladimir Ossipovitch Sherwood, who spent five years in the town from 1860-65 painting portraits of its wealthy families after being brought to Blackburn by John Charles Dickinson who had befriended him in Russia while supplying looms made by his father's foundry to cotton mills there.

But although valuable in itself as an example of one of his works, in terms of Blackburn's history and heritage, it amounts not only to a priceless record of the building of the Cotton Exchange -- a venture that was never completed as grand as it was envisaged and home today of the Apollo Cinema -- but it is also a unique pictorial Who's Who of Victorian Blackburn's prominent people, councillors, mayor, MPs and major manufacturers.

Yet Looking Back discovers that it is only in recent years that the Sherwood painting -- which was cleaned and given a new frame for the Tiplady exhibition -- has enjoyed such high regard. For until the 1960s, it was stuffed out of sight and gathering dust behind lockers in the town's old Technical College building and only came to light when a faraway descendant of one of the people it depicted inquired about it.

Reader Ray Holt, who worked for the town's Education Authority at the time, tells how a letter from Canada arrived at the department in which he worked -- which was concerned with schools furnishings. Why it came to us, I don't know, but it had obviously gone the rounds of other corporation departments which did not want to know," he says.

"It was from a lady who was a distant relative of someone in the painting and she said that she had obtained information that it was stored behind students' lockers in the old Tech."

Ray adds: "A couple of us went across there and eventually we found it behind some wooden lockers down a corridor. Though it's a massive painting it was completely hidden. It was dirty and so dark behind the lockers that we had to borrow a torch from one of the caretakers. At first, I thought it showed some ship's rigging, but that turned out to be the builders' scaffolding.

"We shoved it back and went to the Library, told them where it was and asked them to reply to the letter. We were glad to hand the matter over to them, but I realised something had been done when eventually I saw the painting hanging in the entrance of the Museum and Library building."