The proposal includes plans for three retail units and office space over a total of 11 levels to be built at a gap site at the south end of the centre.

The plans were submitted before the outbreak of the coronavirus.

The south extension of the building is being led by Land Securities and will see vertical infill development over an open-air rail cutting sandwiched between Buchanan Street and Queen Street Station.

Incorporating a new subway entrance from Dundas Square, the expansion will deliver a complex engineering solution devised by Arup to retain ventilation when decking over the railway line while permitting light to the north elevation of the A-listed Dundas House.

An integral part of the work will see Dundas Square upgraded to provide a public space serving as a unified entrance to the new offices, subway and main-line rail services, Urban Realm reports.

Planning permission in principle has already been granted, with an application for detailed consent now being made.

A statement submitted to Glasgow City Council planners reads: “The building will be elegant and simple with a sophisticated palette of materials to create interest and appeal. The most successful office and retail developments have a timeless quality which we hope to achieve with this building.”

If the plans are approved, the developers hope that it would be completed near the end of 2023.