Completed London office space hit its highest level since 2004 between April and September this year in a period which also saw new construction starts rise by almost a quarter on the previous six months.

According to Deloitte Real Estate’s latest London Office Crane Survey, released every six months, 4.2m sq ft of new office space was completed since the previous survey; the highest it’s been since 2004.

The period saw 32 new schemes which is a 23% rise on the previous six months, but in line with the long-term average.

In terms of volume, the 2.6m sq ft the new starts cover represents an 18% drop on the last survey, though Deloitte said this remains ahead of the long-term average of 2m sq ft.

Just over half (53%) of the new start volume is in new builds, equivalent to 1.4m sq ft, while 47% is space undergoing refurbishment. The City is home to 1m sq ft of the new build schemes across four buildings, while the overall 6m sq ft under construction in the City is down 13% on Deloitte’s previous report.

However the 754,000 sq ft started in the West End is the highest volume Deloitte has reported since 2015.

The survey identified a total of 11.8m sq ft of office space under construction across central London by the end of September over 80 schemes, which is down 13% on the previous survey.

Source: Deloitte Real Estate

The report said that while this figure is still above the long-term average, office construction in the capital has been declining since 2016.

But Mike Cracknell, director in the capital projects advisory team at Deloitte Real Estate, said this is down to the “unprecedented completion rates” London is experiencing “rather than any significant reduction in new starts”.

Of the 11.8m sq ft under construction, 6m sq ft is in the City of London with 1.7m sq ft underway in the West End. The Docklands and Kings Cross both had 1.1m sq ft under build at the close of the survey. Midtown had 1m sq ft and Southbank and Paddington had 0.6m sq ft and 0.2m sq ft respectively.

Just under half (49%) of the space under construction has been pre-let with the technology, media and telecoms (TMT) sector accounting for 28% of the deals.

The financial sector followed with 24% of the pre-lets with the corporate sector (including serviced office providers) hot on its tail at 21% of the uptake.

Cracknell identified the war on talent as the driver behind the high rate of pre-lets: “Tenants with larger requirements simply cannot afford to wait for speculative schemes to become available. Locking in the right space is often crucial for attracting talent and driving business growth.”