LONDON (Dow Jones)--Helical Bar PLC (HLCL.LN), a property business, said Friday it has signed an option agreement to purchase the freehold of 1 Mitre Square, London, EC3 from Ansbacher and Co Ltd., together with a long leasehold interest of the adjacent site at International House, Creechurch Lane, from the City Corporation for an undisclosed sum. MAIN FACTS: -The freehold of 1 Mitre Square will be transferred to the City and Helical Bar will have a long leasehold over the entire site. -A planning application has been submitted for a new development comprising 270,000 sq ft NIA of offices and retail on the ground floor. -The site already has full vacant possession so construction could start early next year. -Shares at 0800 GMT up 3.3 pence, or 1.2%, at 289.9 pence valuing the company at GBP310.45 million. -By Ian Walker, Dow Jones Newswires; 44-20-7842-9296; [email protected] (END) Dow Jones Newswires June 11, 2010 04:02 ET (08:02 GMT)