I2 Office has bought rival serviced office group Landmark, which has a flagship operation in the Salesforce Tower in the City, in a move that brings together two of the UK serviced office industry’s largest operators, CoStar News can reveal. i2 Office, which has been run by former MWB Business Exchange chief John Spencer since he left Regus in April of last year, is a rapidly expanding business centre operator in prime city centre locations across the UK. It operates 35 centres, principally in central London but also in Birmingham, Aberdeen, Bristol, Manchester, Edinburgh, Glasgow and Leeds.The group was launched in 2009 and principally occupies Grade A space on traditional 10 year leases in prime locations in major city centres.Landmark is 10 years old and operates six serviced offices in the City and West End prime addresses, notably including 110 Bishopsgate or the Salesforce Tower.It is understood that I2 and Landmark will continue to operate under separate brands.Combined the two companies operate the most serviced offices in the UK after global leader Regus and vie with Business Environment Group for the most workstations after Regus.A spokesman for i2 and Landmark said it was "business as usual".pnorman@costar.co.uk