Having previously said rental values could fall by as much as 7.5 percent, the company now expects values across its office and retail portfolios to range between growth of 1.5 percent and a fall of 2.5 percent for the full year ending March 31, 2018.

"Central London’s commercial property markets have to date proven resilient," the developer said, reporting growth of 0.7 percent in its rental value in the first half of the year.

"We expect the uncertain economic and political environment to weigh on rental levels and yields for secondary properties. However, we remain positive on the long-term prospects for London as a truly global city."

The developer's EPRA net assets per share, a measure of the value of their properties, rose to 813 pence per share in the half year ended 30 Sept 2017 from 808 pence a year earlier.

The value of Great Portland's portfolio of assets, dominated by office spaces but also including retail and residential property, rose 1 percent in the first half to 3.28 billion pounds.

(Reporting by Hanna Paul in Bengaluru; editing by Patrick Graham)