HSBC Group has agreed the sale and leaseback of its iconic 45-storey Docklands head office building in Canary Wharf, London for £1.09 billion.

The sale of the 1.1 million square feet tower, which cost £500 million to build and is home to 8000 HSBC staff, is the largest single property deal in UK history.

HSBC’s 210-metre high tower at 8 Canada Square will remain the group’s global headquarters.

A wholly-owned subsidiary of Metrovacesa, S.A., one of Europe’s most respected property companies and Spain’s biggest listed property company, and HSBC have exchanged contracts on the deal which sees the bank retain full control of occupancy while Metrovacesa takes a 998-year lease.

HSBC has leased the building back for 20 years at an annual rent of £43.5 million with an option to extend for a further five years.

HSBC, which became the first bank to go “carbon neutral” in 2005, last year achieved an overall rating of ‘Excellent’ for the head office building from the Building Research Establishment (BRE), the UK’s leading environmental standards authority. Key to the building’s design is the use of energy efficient systems and practices.