Almost 50 years since it was last seen, the Oak Room - the largest Charles Rennie Mackintosh interior for Miss Cranston's Ingram Street Tearooms in Glasgow - is to be resurrected for the new £80m V&A Museum of Design in Dundee.

The unique tea room, which is 13.5m long, will be the centrepiece of the museum's design galleries when it opens to the public in 2018.

Long in storage, the Oak Room was designed by Mackintosh for the Ingram Street tearoom in 1907 and completed in 1908.

The re-assembling of the tea room will be a joint project between Glasgow Museums and the V&A and will be the first time the room has left Glasgow.

The tea room is being given to the V&A as a long term loan from Glasgow Life, the arms length body that runs the city's museums and galleries, and funding from the Heritage Lottery Fund.

The tea room panels were salvaged in the 1970s and have long been largely in storage - the V&A show will be the first time the 600 surviving pieces of the interior will be reassembled and put on public display.

The interior last functioned as a tearoom in the early 1950s.

Only a very small part of the room has ever been on display at Kelvingrove Art Gallery and Museum since the interior's removal from the original building in 1971.

Councillor Archie Graham, the chair of Glasgow Life and depute leader of Glasgow City Council, said: "This is a fantastic example of joint working, which will bring back this lost gem for public display, confirming Mackintosh's unique and internationally significant contribution to Scottish design history.

"Each time our staff work on these rooms they discover Mackintosh's ingenuity for creatively arranging interior spaces into complete works of art.

"We hope this exciting collaborative project will allow us to uncover many more of Mackintosh's design secrets for everyone to enjoy."

The conservation, restoration and reassembly of the Oak Room will be "complex" the council said.

When the tearooms were removed each room was numbered, each wall given a reference, and each piece of panelling coded.

Plans and elevations of the rooms were drawn to show how everything fitted together.

Between 2004-5, with the help of this coded information Glasgow Museums quantified and documented all surviving Oak Room panelling.

Scottish Government funding enabled the developmental stage that has informed the work which will now take place to recreate the room.

The interiors of the Ingram Street Tearooms designed by Charles Rennie Mackintosh between 1900 and 1911 are unique.

Designed for tearoom entrepreneur Miss Catherine Cranston, Mackintosh's suite of interiors was shop-fitted into the ground floor and basement of a Victorian warehouse and office premises at 205-17 Ingram Street.

They were one of four city-centre tearoom premises Mackintosh worked on for Miss Cranston - the others being on Buchanan Street, Argyle Street and Sauchiehall Street (The Willow Tea Rooms).

The Ingram Street premises remained in use as tearooms until 1951, after which they were used as shops and storage spaces.

The interiors were documented and removed in 1971 to enable the building to be converted into a hotel.

Since 1984 small sections of the tearooms have been on display in Glasgow.

Philip Long, Director of V&A Dundee, said: "V&A Dundee will celebrate the best of Scottish and international design creativity.

"When we set about planning the Scottish Design Galleries for V&A Dundee it was vital Mackintosh, recognised around the world as one of the great and most influential of designers, was represented appropriately.

"It is extremely fitting that the public will be able to see such a major work by him at the heart of that story."

Joanna Norman, senior curator at the V&A and lead curator for the Scottish Design Galleries, said: "This major conservation project preserves and presents an outstanding piece of Scottish design heritage for a broad public audience.

"It is extremely exciting that it will be unveiled at the opening of V&A Dundee in 2018, the 150th anniversary of Mackintosh's birth.

"The Oak Room will be the only historic interior on display in our galleries and its reassembly will allow visitors to immerse themselves fully in the brilliance of Mackintosh's spatial and decorative design."