Lloyd's has unveiled plans to radically modernise its offices to accommodate more staff.

As part of the changes, the ground floor will be redeveloped, with Gallery 11 hosting a new “visual sculpture” of people working in the market.

The renovations have been prompted by the sale of Lloyd's 1958 building to property developer British Land. The 400 staff currently working in the 1958 building will relocate to the Lloyd's building at One Lime Street, before the end of December and space must be made for them.

Earlier this year, the fifth floor of One Lime Street was completely rebuilt to accommodate its regulatory and legal team. Now there are plans to move the Nelson Collection, the biggest display of Lord Nelson's possessions, from the concourse to the basement area.

The building will also have to provide catering facilities for all its staff – its two existing restaurants are to be knocked down and joined together. Both have now closed for refurbishment.

Gallery 11, which has not been touched since the building first opened in 1986, will also be modernised. Offices for an additional 20 staff have already been constructed.

In addition, the floor will host the “Millennium Image”, a single image made up of ten photographs of 2,000 people in the underwriting room, mounted on 5ft-high metal stands. This will rotate round 360 degrees and will replace the old display cases, becoming the centre piece of the gallery.

Spokesman for Lloyd's, Adrian Beeby, said: “Lloyd's has a tradition of moving buildings throughout its 300-year history and this move will require considerable restructuring of the two floors.

“The ‘Millennium Image' will add a more modern flavour and will document the market at the turn of the millennium, in comparison with the big pictures from the 1940s and 1960s.”

The sculpture, which is being created by Mike Rolls, will feature more women, younger people and mixed races. The ten images were taken over a three-day period, as people had to be arranged in each of the photographs in turn.

As a school boy prank, some staff ran from one side of the room to the other during the operation.

“People were spotted appearing in the picture twice,” said Beeby. “But they were removed using computer technology. Others who were never there were also added in.”