Dr Simon Thurley, chief executive of English Heritage, is opening Clifton House as part of Lynn Festival and is hoping to add to the building's wealth of history by learning more about how it was used over the past 50 years.

The Clifton House story starts in 1250, when the original house was built, and over the following 800 years it was owned by a series of wealthy wine merchants who invested money in rebuilding and remodelling it, adding to it and fitting it out with the fashions of the time.

But despite successfully charting the long and proud history of the house Dr Thurley only has limited information from the more recent era.

He said: "It is probably Lynn's oldest and most historic house. We have a surprising amount of information on how it was in early times and have found out all sorts of interesting things but the gap, bizarrely, is what has happened in the last 50 years.

"It was council offices after the Second World War and I am certain that many people are still around who remember it as offices.

"There is very little information about the people who lived there and how the council offices worked, it would be really useful to fill in those years.

"What I would really like is a photograph of the interior in use as an office. Then it was occupied by two people, Mr Foster and Colonel Catt. I have a photograph of Mr Foster but not the Colonel."

The house, in Queen Street, will be open from 11am to 4pm on Saturday and visitors will be able to enjoy the many different rooms and view a special exhibition with photographs and objects from over the years.

Dr Thurley said: "We are opening more or less the whole of the house. We have now reached a stage where people have the opportunity to see inside but we have got at least another two years work to do.

"Visitors will also be able to go up the tower and enjoy views from the top."