One London tower plans set 2033 skyline marker

Plans for One London have put a new marker down in the City’s high-rise office pipeline, with the £1bn-plus scheme expected to become the tallest tower in the Square Mile if delivered to its planned 309.6m height.

Aroland Holdings, advised by Perennial Holdings, is working with Stanhope and Eric Parry Architects on the project, formerly known as 1 Undershaft. The development is planned for the junction of Leadenhall Street and St Mary Axe, within the City’s eastern cluster of commercial towers.

The scheme is designed to provide around 1.2m sq ft of office-led floorspace, supported by public-facing elements and improvements around the base of the building. Its height would place it alongside the capital’s most prominent tall buildings, while its location gives it a direct relationship with the surrounding cluster of towers, heritage assets, transport links, and heavily used public streets.

Full planning consent has already been secured from the City of London Corporation. Deconstruction of the existing St Helen’s Tower is under way, with a main contractor appointment expected later this year. Construction is planned to begin in 2028 after deconstruction, enabling works, and development financing have been completed, with completion targeted for 2033.

Although office demand has softened across weaker secondary stock, the City’s development pipeline is increasingly concentrated around buildings that can offer high energy performance, strong amenity, flexible floorplates, and a more generous workplace environment. One London is being advanced in that more selective market, where occupiers are consolidating into fewer but better buildings rather than simply reducing space without regard for quality.

For the construction team, the scheme would sit at the complex end of commercial building delivery. High-rise work in the City brings constrained logistics, tight access, basement and structural interfaces, heavy lifting, façade engineering, building services coordination, and public realm delivery within one of the most restricted construction environments in the country. The deconstruction phase also carries its own technical demands, particularly where an existing tower must be removed safely within a dense commercial district.

The City office market is already producing a steady stream of redevelopment proposals that attempt to balance commercial density with carbon, public realm, and changing occupier requirements. Lipton Rogers’ approved 1 Silk Street office redevelopment points to the same pressure: central London sites still attract major investment where location, specification, and long-term rental prospects support the case for redevelopment.

Embodied carbon scrutiny will remain a defining issue for One London as the project moves towards procurement and construction. A tower of this scale carries significant demand for steel, concrete, façade systems, lifts, MEP equipment, fit-out materials, logistics, and temporary works. Planning approval does not remove the need to demonstrate that redevelopment can justify itself against refurbishment or lower-carbon alternatives.

Public access and ground-level use will also be closely watched. Tall buildings in the City are now expected to do more than deliver commercial floor area. They must contribute to street-level permeability, civic space, cultural use, and a more open relationship with the surrounding public realm. Those requirements make the lower levels of the building particularly complex, because they sit at the intersection of planning, commercial operation, security, servicing, and public use.

The next construction milestone will be the appointment of a main contractor. That decision will begin to turn the project from an approved skyline proposal into a delivery programme, with procurement, programme certainty, logistics, cost control, and carbon management all tested over a construction cycle that stretches into the next decade.