Office rents in central London are soaring at their fastest rate for seven years, according to research published today by Knight Frank. Financial Times

Grade A rents in the City of London have leapt in the last year by 25% from £49/sq ft to £61.50/sq ft. West End rents have also risen by 26% from £85/sq ft to £107.50/sq ft.

Landlords had also slashed incentives. Whereas two years ago it was common for rent-free periods of two years to be offered in return for agreeing to a 15-year lease, now only one year is offered.

Since 2003, vacancy rates have fallen from 11.6% to 3.8% in the West End and from 13.7% to 6.6% in the City. The Docklands vacancy rate has fallen from 13.5% to 5.8%, and it is understood that Canary Wharf now has almost no space for letting.