Tullow Oil has started the registration process in the UK and hopes to be fully listed on the oil and gas index there by the middle of next year, managing director Mr Aidan Heavey said yesterday after the company's e.g.m, which approved a new stock issue. He said the absence of registration and a listing on the UK oil and gas index meant that some institutions had not invested in the £18.3 million of new stock , all of which had already been placed with many of the UK's leading blue-chip companies.