Landsec and Canary Wharf Group have exchanged contracts to sell the Walkie Talkie, EC3, to LKK Health Products Group for £1.28bn – the UK’s largest ever office deal.The price reflects a net initial yield of 3.4%.Completion is expected to take place at the end of August and is unconditional.The trophy office building at 20 Fenchurch Street was developed by a joint venture between Landsec and Canary Wharf Group in 2010, completed in 2014 and comprises 671,000 sq ft of office space over 34 floors in the City’s insurance district.Canary Wharf Group, the Qatari Investment Authority, China Investment Corp, Morgan Stanley Real Estate Investment and Brookfield Property Partners instructed CBRE and Eastdil earlier this year to sell their 50% stake for around £600m.Landsec has not actively marketed the remaining 50% stake it owns. However, Landsec chief executive Rob Noel told EG in May that the REIT would “always accept a strong bid for any asset when we think we can use the money better elsewhere.”Robert Noel, Chief Executive of Landsec, said: “Our decision to sell 20 Fenchurch Street at an exceptional price and return cash to shareholders reflects our disciplined approach to the use of capital.”Sir George Iacobescu, chief executive of Canary Wharf Group, said: “We are immensely proud to have built and developed what has become one of the City of London’s most iconic buildings in an exceptional joint venture with Land Securities. 20 Fenchurch Street is an illustration of the large, high specification and bespoke buildings that Canary Wharf Group is renowned for. We are delighted that in its creation we have helped to sustain thousands of jobs in its construction and deliver significant improvements to public space in the heart of London.”Cushman & Wakefield advised LKK.