Census records detailing the lives of around 275,000 people which were rendered illegible in floods more than 100 years ago have been transcribed and published online for the first time.

Documents collected in Manchester for the 1851 poll have lain untouched in storage at the National Archives. But experts have used photographic technology to see through the mould and flood damage which rendered the documents illegible.

They believe their painstaking work, involving photographic techniques more commonly seen on crime scenes, will make it possible for as many as 150,000 people to trace their ancestors.

Jack Reese, the Ancestry.co.uk expert who completed the work begun 20 years ago by the Manchester & Lancashire Family History Society, said the “seemingly blank pages and scraps of paper” had been turned into “a hugely valuable set of historical records”. He added: “Digitizing and transcribing them has preserved them for future generations.

“Undertaking a project of this size has been a fascinating journey, but the most exciting part will be when people start finding their ‘lost’ ancestors in the restored records."

The “Lost Souls”, records of whom were thought to be erased by the flooding, came mainly from the Manchester area. Census records are normally made available on microfilm at the National Archives but those damaged by the flood in the late 19th century were in such poor condition, they were not filmed and around 17,000 of them were thought lost.

But Mr Reese and his team used short wave UV light to reveal the faded writing on the pages. Since the rays are hazardous to human skin and vision, a bespoke ‘black box camera’ system was used to expose the pages and reveal the faded, often near-invisible writing. They were then photographed and transcribed.

Census records are gathered every ten years, the first time being in 1801. Early polls recorded no details and merely gathered figures but later records, beginning in 1841 provided more and more of an insight into people’s lives. And the 1851 records are the first to give occupation, address and year and place of birth and are now published online at Ancestry.co.uk.

Among the records are those of Samuel Bamford, an English radical and writer from Middleton. Bamford was a voice for parliamentary reform and the repeal of the Corn Laws, but opposed to any activism that involved physical force. His poetry sympathised with the conditions of the working class and when he died he was given a public funeral attended by thousands

A snapshot of the life of Edward Riley Langworthy, a Liberal politician and businessman, is also included. Riley Langworthy established a cotton business in Salford and went on to become the town’s Mayor. He also oversaw the establishment of the free public museum and library in the borough.

Found a member of your family among the records? Send your stories in to k.rawlinson@independent.co.uk