BRITAIN'S Conservative government has committed itself to a comprehensive Citizen's Charter aimed at giving citizens an extensive range of rights and access to public information so far denied them.Prime Minister John Major hopes the package of more than 100 measures unveiled in the House of Commons Monday will help his party win the next general election. On Tuesday, Mr. Major wrote to more than 500,000 civil servants telling them that in the future they can expect to be held accountable to the public they serve. Public officials will be required to wear name tags so that Britain's 50 million citizens will know whom they are dealing with. Jonathan Clark, a historian at Oxford University, compared the new policies to Magna Carta, the bill of rights granted in 1215 by King John to the barons of England. He describes the initiative as "an astonishingly ambitious attempt to create a public mood." "It embodies a brilliant insight," he says. "Consumer issues are at the center of modern politics." The core of the Citizen's Charter is contained in a government White Paper. A series of individual charters, backed up by primary legislation, is planned for later in the year. * British Rail will be required to publish its own "passengers' charter" in the fall, detailing the rights of train-users: for example, advising consumers how to get their money back if their trains are canceled or run late. * The government plans to publish a "parents' charter" later in the summer. Schools will be required to provide parents with detailed information on their children's progress and local authorities must publish a "league table" of standards achieved in individual schools. * Police forces will be required to set and publish target times for answering telephone calls and arriving at the scene of incidents. * One of the more controversial of the Major's measures will ensure that hospital patients required to wait more than two years for treatment under the National Health Service will be able to obtain it, free of charge, from private hospitals. * Regulators in the water, gas, electrical and telecommunications industries will be given enhanced powers. Reaction in some areas of the public services targeted by the Citizen's Charter was predictably sour. Rodney Bickerstaffe, general secretary of the public employees' union, condemned it as a "government gimmick." "This candyfloss charter is a pathetic parody of a consumer-rights package," he said. A spokesman for English local authorities whose employees will have to meet the charter's demands said the best means of quality control was ensuring accountability through the ballot box, not giving people rights that might not be enforceable. Britain's leading consumer organization, however, suggested that the charter did not go far enough in some areas. The Consumers' Association questioned whether it would solve the problem of "complacent management" at the top of large service industries. Labour Party leaders, on the other hand, were quick to condemn the proposal. Opposition leader Neil Kinnock, aware that the prime minister regards the Citizen's Charter as a potent weapon in a campaign to win the general election due in under a year, called it a mixture of "the belated, the ineffectual, and the banal." Major retorted: "It will be a milestone for us. But I suspect it will be a headstone for the Labour Party." Mr. Kinnock also attacked Major for failing to give details of what the Citizen's Charter would cost. The prime minister, however, said the price to be paid would be determined in the annual round of public spending negotiations between the Treasury and government departments now getting under way. A government official said the cost of the charter was likely to be "modest." Privately, however, Labour party strategists are expressing worries that Major may have produced an election-winning formula in the era of post-Thatcherism. Major and his advisers hope that publication of the charter at a time when the political parties are preparing for a general election could turn out to be a masterstroke. Kinnock reflected his party's concern on this point when he complained that many of the features of the charter had been taken over from Labour policy documents published in the last few months. Stanley Orme, chairman of the Labour Party, described Major's initiative as "not so much a citizen's charter as an election address from the Conservative party." A Downing Street source said the approach underlying the Citizen's Charter is distinctly different from that of Margaret Thatcher, Major's long-serving predecessor. The source commented: "Mrs. Thatcher, when faced with public services that were not delivering the goods, tended to propose that they be privatized. John Major is more inclined to make the public services meet the standards that one expects in the private sector."