One index of the revival in fortunes of privately owned country houses from the mid-1970s was the sharp fall after this point in the number of houses being offered to the National Trust. Those mansion properties that are nowadays held ‘in trust for the nation’ by either of the UK's National Trusts are mainly legacies of the post-war slump in country house fortunes in the 1940s and 1950s. Compared to this earlier phase of growth, relatively few mansion properties have been acquired by either of the Trusts since the conditions for country house owners improved so markedly after the finance acts of 1975 and 1976.

Perhaps we should not be so surprised by this. In many ways the high period of country house acquisition by the National Trust, from the 1940s to the early 1970s, was an aberration from its founding mission. When the Trust was established in 1895, its focus was not so much on houses, or even on built heritage more generally, but on land and landscape. The social housing cam-paigner Octavia Hill is often presented as the Trust's founding spirit, given the missionary zeal with which she pursued her energetic campaigns to improve the lives of the poorest in society. Yet at the very heart of the National Trust was an idea about legal rights to property and ownership, which was wholly original, indeed radical, in its conception. For this, the Trust's founding chairman, the lawyer Robert Hunter, deserved full intellectual credit.

The ability to hold land in trust was not itself original. Such concepts dated back to the Middle Ages, developed, it was said, to ensure that the estates of crusading knights were protected during their long periods of absence. Houses and estates might be placed into trust in situations where an heir inherited before his majority, or where the owner was incapacitated because of illness or some other misfortune. Trustees for estates took responsibility for the property and sought to manage it not for personal gain but in the interests of beneficiaries. Landed estates could be further bound by the practice of entail, where an owner was cast as merely a temporary custodian, holding property on behalf of as-yet-unborn heirs.