Three independent television companies and the news agency Reuters Ltd. announced yesterday a takeover bid for troubled Independent Television News Ltd.Carlton Communications PLC, London Weekend Television, Central Television and Reuters Ltd. offered to inject $ 51.3 million, in return for an 80% stake in ITN. Under the deal, Hambros Bank would acquire on behalf of the consortium all of ITN’s 400,000 existing shares — other than those already held by Central or London Weekend Television — for $ 1.71 a share. The offer depends on ITN securing a five-year contract to supply news to Independent Television (ITV), one of Britain’s two independent television channels. The 1990 Broadcasting Act required ITN to transform itself from a wholly owned subsidiary of ITV into an independent, profit-making organization. But cost-cutting efforts have not proved wholly successful. ITN chief executive Robert Phillif said his board will consider the offer at a meeting on Monday, along with a final proposal for the ITV news contract. “Both these developments are positive indications of confidence in the future of ITN,” he said, promising the board’s “most careful consideration” of the offer. “The Carlton consortium approach underlines what we have believed for some time: that ITN has a significant value. . .” The consortium will put its proposals to ITN’s shareholders today. During tough negotiations with ITV over the news contract, ITN has trimmed costs by cutting staff to 650, from 1,000 at ’91′s start. But its failure to find tenants for its new London headquarters have cost it an estimated $ 8.55 million a year, said a spokesman. Carlton Communications, a publishing and entertainment company, in 1991 successfully bid $ 74 million a year for the weekday license to broadcast television in the London area, previously operated by Thames Television PLC. It begins transmissions in January. The consortium is led by Carlton Communications chairman Michael Green.