CONTAINED within the walls of Swindon’s Engine House is a remarkable and irreplaceable collection of photographs, drawings, reports and plans, recording the architecture and archaeology of England.

If you want to find out about the evolution of Swindon, or the detailing on a Georgian mansion, the remains of field systems created by medieval farmers, or what a Woolworth’s store looked like, this is the place to visit.

The Historic England Archive is an ever-expanding treasury of information on the ways humans have interacted with their environment – to grow food, work, celebrate and worship. It holds some 12 million items, with a hoard of on-line resources, offering, for example, a chance to see pictures of towns and villages across England from the earliest days of photography.

“It’s a record of our historic environment, and how we care for it,” said Mike Evans, head of the Historic England Archive.

“It tells us what buildings looked like and how people lived in them, from prehistoric times to the present day.

“It’s not just bricks and mortar, but people as well.”

The Engine House, in Fire Fly Avenue, is an impressive Grade II Listed four-storey building on the site of the Great Western Railway works, built in the 19th century to provide offices for the railway industry. English Heritage took it over in 1992 to house the archive.

The Historic England Archive has evolved over the decades, with its roots in the Royal Commission on the Historical Monuments of England, a government advisory body established in 1908 to document buildings and monuments of historic importance.

In 1999 it merged with English Heritage, and in 2015 English Heritage divided into two parts – English Heritage now being a charity that manages historic buildings and sites such as Stonehenge, while Historic England has the job of protecting listing historic buildings and helping protect the historic environment.

It has an office in London, which is responsible for the listing and Government advisory side of things, and some regional offices, while Swindon is home to Historic England’s extraordinary archive.

Some 75 per cent of the archive is made up of photographs, dating back to the earliest days of the medium in the 1840s. Anyone interested in England’s history can search over a million photos and documents online – including detailed drawings and reports on historic buildings, and surveys of archaeological sites like Roman forts and medieval villages.

The archive has many fascinating collections of pictures, including Britain From Above – some 95 thousand pictures of the UK from the Aerofilms collection, mostly taken between 1919 and 1953, and England’s Places – a collection of 600 thousand pictures organised geographically to show buildings and architecture across the country from the mid-19th century to the 1990s.

About 50 people work on the archive, including archive services staff who help people with their research and enquiries, and conservation specialists.

Photographic conservator Jenny Harvey is one of the expert team tasked with repairing and conserving photographs, so they last as long as possible.

“We do remedial work, making items as physically and chemically stable as we can,” she explained. “We want them to be usable and accessible, so we are able to scan them and get them out to the public.

“We have a number of treatments and solutions, to repair glass plate negatives, or torn prints.”

Some have been badly mounted, or fixed with animal glues. Photographs fade and later over time as the chemicals they are made of alter or decompose.

And digitising images is no guarantee of immortality, she said. Images on CDs may only last for five years.

Keith Austin is archive resources team leader, and shows us around the purpose-built storage facility – which was state of the art when it was completed in 1994 and was refurbished with new air conditioning three years ago.

This is an impressive extension, spread over four floors, and capable of holding the archive at a temperature of six degrees centigrade and 32 per cent humidity. If someone wishes to see some of the precious photographs and images, the items have to be stored overnight and acclimatised in stainless steel cells before being moved into a normally warm, humid environment, so they are not affected by condensation.

“Photographs are constantly deteriorating, and we are trying to conserve them forever,” Keith explained.

Archive services team leader Alyson Rogers helps people use the archive effectively – whether they are looking for resources to help in a property boundary dispute, for information to help restore an old building to its former glory, carrying out research for A levels or simply curious to find out how their local area might have changed over time.

“We deal with about seven thousand enquiries in a year,” she said. “People can ask us what we have got, and we offer a copying service. Many enquiries are done remotely.”

They have even helped out in the making of movies.

“We were asked for sample pictures of the cloisters of Gloucester Cathedral – afterwards we realised these were used as illustrations for possible sets for the Harry Potter films,” she said.

Alyson and her team can advise people who visit how to get the best from their time at the archive, and they can organise tours. And she said her job never fails to be fascinating, working with such a huge resource of visual history.

“With 12 million items in the archive, there is not a day goes by when someone doesn’t say, have a look at this,” she said. “And it is amazing when you realise that a photo means a lot to someone – perhaps they’ve identified a relative in a picture, and when you hear people’s stories.”

The Historic England Archive catalogue is accessible via their website, HistoricEngland.org.uk, where you can search over a million entries from the catalogue. If you cannot find what you are looking for, you can contact archive staff for help. You can also carry out your own research in the Public Search Room, by appointment.

The archive also has a reference library of journals, periodicals and books at The Engine House, that is open to visitors from Tuesday to Friday, 9.30am to 5pm. Tours can of the archive can be arranged but must be booked in advance. Historic England also publishes a range of books, which are available through the website.