Laing O'Rourke is the most active residential contractor in the capital, with projects totalling more than 2500 units.

The company leads the table of top contractors in the Blue Book 2006, a report on the contractors and consultants working in residential development in the capital, which is due to be published by London Development Research next month.

The researchers assessed 359 residential schemes under construction in London’s 33 boroughs. More than 80% of those schemes comprised apartments. The contractor listing is based on the 186 schemes being carried out by a main contractor, rather than by the developer itself.

Tim Craine, managing director of London Development Research, said the top two contractors reflect the very different types of housebuilding activity in the capital. Laing O'Rourke’s schemes include high-density private-sector-led mixed-use projects such as Berkeley Homes’ Tabard Square in Borough, south London, which has more than 500 apartments as well as commercial space and includes a 22-storey tower.

Second-placed contractor Willmott Dixon is working mainly in outer London boroughs and has a bigger focus on housing regeneration projects, such as the redevelopment of the Church End Estate in Brent for registered social landlord Catalyst Housing Group.