Land Securities has agreed to buy the leasehold interest in an 1.9 acre site in East London for £16.5m.The site includes vacated 1970s offices and a TfL worksite at 21 Moorfields, EC2.Land Securities entered into a conditional agreement to acquire the site in December 2012 before receiving the green light for a new development head lease with TfL.The company will own the site on two separate 250 year leases at ground rents of 5% of the net rents received.