Clark believed in making fine art accessible to everyone, and while at the National Gallery he devised many initiatives with this aim in mind. In an editorial, "The Burlington Magazine" said, "Clark put all his insight and imagination into making the National Gallery a more sympathetic place in which the visitor could enjoy a great collection of European paintings". He had rooms re-hung and frames improved; by 1935 he had achieved the installation of a laboratory and introduced electric lighting, which made evening opening possible for the first time. A programme of cleaning was begun, despite sporadic sniping from those opposed in principle to cleaning old pictures; experimentally, the glass was removed from some pictures. In several years he had the gallery opened two hours earlier than usual on the day of the FA Cup Final, for the benefit of people coming to London for the match.