By Charlotte Higgins
http://www.guardian.co.uk/artanddesign/2013/feb/19/old-masters-paintings-denis-mahon

A collection of 57 old masters worth around £100m – some bought for as little as £100 apiece in the mid-20th century – are to be formally given to the nation, with strings attached. If any attempt is made by the host museum to charge for admission; or any item from their collection is put up for sale, the Art Fund, the charity that is donating them, can take them back.

The conditions attached to the donation of the works, among them paintings by Guercino, Guido Reni and Luca Giordano, are in line with the wishes of the collector who amassed them: art historian Sir Denis Mahon, who died in 2011, aged 100.

The conditions seem especially resonant now, as museums suffer funding cuts and charging for admission is again being reluctantly considered in some quarters. There are also increasing examples of public bodies selling artworks to help plug financial holes – as with the attempt by Tower Hamlets council in London to sell a Henry Moore sculpture that the artist had intended for public display.

According to Stephen Deuchar, chief executive of the Art Fund, the conditions "keep up the pressure for governments to do the right thing by museums and galleries".

Mahon, heir to the Guinness Mahon banking fortune, built an extraordinary collection of mainly Italian 17th-century paintings, without ever spending more than £2,000 per picture. He left 57 works to the Art Fund with the arrangement that they should be on long-term loan to a selection of British galleries: eight to the National Gallery of Scotland in Edinburgh, 25 to the National Gallery in London, 12 to the Ashmolean in Oxford, six to the Fitzwilliam in Cambridge, five to the Birmingham Art Gallery and one to Temple Newsam House in Leeds.

The final stage of his bequest is now complete, with the formal transference of the 57 works' ownership to the various museums. Though the paintings are already in situ – regular visitors to the National Gallery in London will recognise, for example, Guido Reni's Rape of Europa, with the mythical heroine, clad in saffron and fuchsia, being borne away over the waves on the back of Zeus, disguised as a bull – but they are now accompanied by smart new signs, announcing "new acquisition".

Deuchar emphasised the political commitment of Mahon, who "will be remembered as a robust and ruthless arts lobbyist, campaigning for, above all else, free admission to national museums and galleries and against the selling of collections".

Christopher Brown, the director of the Ashmolean Museum, remembered a man of exceptional erudition: "There was no more enjoyable and illuminating way of looking at paintings than in his company. Poussin, Carracci, Guercino: he spoke about them as if he knew them."

Brown recalled how Mahon's love of art began: Nikolaus Pevsner, with whom he studied at the Courtauld Institute, suggested he study Guercino, and he gradually began to create his own collection of Italian seicento works, which were then wildly unfashionable. He offered a Guercino to the National Gallery at the price he had paid for it – £200 – but they turned it down. "That gave him the idea of holding a collection until the national museums came round to his taste" – which, eventually, they did, not least through Mahon's vigorous efforts.

His public-spirited desire to have his collection end up in the public realm was "completely free of vanity", said Penny. He was supremely uninterested in having his "name inscribed on a particular room" and was happy that his collection should be dispersed around Britain.