The largest expanse of Roman mosaic found in London for more than half a century has been unearthed at a site believed to have been a venue for high-ranking officials to lounge in while being served food and drink.

Dating from the late second century to the early third century, the mosaic’s flowers and geometric patterns were a thrilling, once-in-a-lifetime find, said Antonietta Lerz, of the Museum of London Archaeology (Mola).

It was discovered about a month ago at a construction site near London Bridge. The mosaic, which is eight metres long, will be lifted later this year for preservation and conservation work, with the eventual hope of it being publicly displayed.

Its main panel features large, colourful flowers surrounded by bands incorporating a twisted-rope design, set within a red tessellated floor.

There are also geometric elements and lotus flowers in the main mosaic and a smaller nearby panel.

David Neal, an expert in Roman mosaic, has attributed the design of the larger panel to a team of mosaicists known as the Acanthus group, who developed a unique style.

The smaller panel is a close parallel to one unearthed in Trier, Germany, suggesting that London artisans travelled abroad.

The archaeologists from Mola, who have worked at the site since last June, believe the room housing the mosaic was a triclinium, containing dining couches on which people would recline to eat and drink while admiring the decorative flooring. The walls were also richly decorated.

The triclinium may have been part of a Roman mansio, effectively an upmarket motel offering accommodation, dining and stabling to state officials and couriers travelling to and from Londinium across the river.

The footprint of the building is still being uncovered, but it appears to have been a large complex around a central courtyard.

Another large Roman building was also found at the site, which archaeologists say was likely to have been the private residence of a wealthy individual or family. Traces of lavishly painted walls, terrazzo and mosaic floors, coins and jewellery have been found.

Among the items recovered are a decorated bronze brooch, a bone hairpin and a sewing needle. “These finds are associated with high-status women who were following the latest fashions and the latest hairstyles,” said Lerz.

It was “the heyday of Roman London”, she added. “The buildings on this site were of very high status. The people living here were living the good life.”

The site is being redeveloped as The Liberty of Southwark, a complex of offices, homes and shops that is a joint-venture by U+I and Transport for London.