The National Trust in Britain, together with similar voluntary organizations, plays an increasingly important part in the preservation for public enjoyment of the best that is left unspoiled of the British countryside. Although the Trust has received practical and moral support from the government, it is not a rich government, supported by public taxes. It is a voluntary association of people who care for the unspoiled countryside and the ancient sites to preserve them for the permanent enjoyment of the public. It is a charity, which depends for its existence on voluntary support from members of the public. It has 160,000 members in England, Wales and Northern Ireland who pay a small subscription each year, and its primary duties are to protect for the nation places of great natural beauty and places of historical interest and preserve them from the dangers of modem development and extinction. The attention of the public was first drawn to the dangers threatening the great old houses and castles of Britain by the late Lord Lothian, who in 1935 said that, as a result of taxation and estate duty, most of these ancient houses were under sentence of death. When he died he left his great seventh century house and all its contents to the Trust Together with 4,500-acre park and estate surrounding it. This gift attracted wide publicity and it started the Trust's 'Country House Scheme'. Under the scheme, with the cooperation of the government and thanks to the generosity of the general public, the Trust has been able to save and make accessible to the public about one hundred and fifty of these old houses, together with often very valuable contents. Whenever possible, the Trust seeks to maintain continuity and to preserve these as living realities rather than as dead museums. It is the view of the Trust that the families who give them to the nation and whose ancestors created them make the best possible curators. In addition to country houses and open spaces the Trust now owns some examples of ancient wind and water mills, gardens, Roman antiquities, farms and small villages, cultural parks, as well as complete villages. In these villages no one is allowed to build, develop or disturb the old village environment and all houses completely maintain their original sixteenth-century style. The public definitely has free access to these areas and is only asked to respect the peace, beauty and wildlife. The preservation was part of history of Britain, and is now practiced by its organization, certainly will be carried on in the future, therefore, those cultural and historical relics will exist forever as long as people care for the environment in which they are living, both natural and cultural. What is the possible meaning of 'subscription' in the first paragraph?