Prime rents in the City of London are now lower than they were 25 years ago, when Big Bang ushered in American and European investment banks with a seemingly limitless appetite for office space.

After taking account of rent-free periods of two years, space now fetches an effective £44.90 per sq ft, 5.5% lower than the £47.50 of 25 years ago. During that period they have been lower. In 1992 City rents fell to £24.40, five years after they surged to their post-Big Bang record of £66.50 per sq ft.