The Italian-born Gilbert Prousch and the British-born George Passmore first met when they were sculpture students at London's Saint Martin's School of Art in 1967 and it was love at first sight, although they did not formally marry until 2008. Despite their protestations that they were poor country kids who did not fit into the arts establishment, they have become core establishment figures who represented Britain at the Venice Biennale and were the subject of a major retrospective at Tate Modern. They are also known for their conservative political views as monarchists and strong supporters of former prime minister Margaret Thatcher.

As artists, their main conceptual innovation was that like the Dada artists before them, Gilbert and George could themselves become art works. Their early signature piece was as singing sculptures, where with faces smeared with metallic paint and immaculately dressed in conservative suits, they sang Flanagan and Allen's somewhat banal song Underneath the Arches. They sang it in London, then at Dusseldorf and New York, where the performance went for a continuous eight hours. They travelled with it to Australia in 1973 and performed it in Melbourne and Sydney and most recently on Tuesday night at the gallery in Canberra.

Articulate, well-informed and media-savvy, Gilbert and George proclaimed that they were "poor enough that we needed to succeed" and by walking the streets of London "we realised that we could be living sculptures". Not everyone loved them, but everyone noticed them. Next came the expletives where their posters declared "George the c---, Gilbert the s---". As they explained in Canberra, they were up front and full frontal, "we tried to abuse ourselves before they could abuse us … It was a pre-emptive strike". Again the Canberra performance contained a virtuoso stand-up duet of combinations of expletives as a comprehensive philosophy of life.

Living in London's East End, more specifically Fournier Street, Spitalfields in a fully restored 18th-century house, Gilbert and George state that they are insulated from the art world and spend their lives in the East End and making art exclusively in their house. In Canberra they repeated their boast "we never liked art about art, but art about life". Their newly acquired piece for the gallery from 2014, based on the Crusader alarm systems in London, is in their patented polychrome style featuring the somewhat exaggerated heads of two artists within a dense maze resembling heavy leadlighting of stained glass windows.

The new presentation of international art at the National Gallery is spectacular, with most of the internal partitions removed, allowing for sweeping vistas. Blue Poles glows under the new LED lighting, the Malevich looks marvellous displayed on its own separate wall, and the treasures of the New York School have a breathing luminosity. Three of the highlights of the new hang include the special display of the Tyler Graphics with the Frank Stella appearing better than ever. The Russian material, with the Goncharova neo-primitive canvas, the Ballets Russes costumes and the Suprematicist ceramics glow and sparkle, while the David Hockney gallery shows the substantial Hockney holdings to advantage. If I have a criticism, it is with the Brancusi birds. Although dramatically lit, they look less convincing in their tub of concrete and I did love them downstairs set within their pool of water creating a meditative oasis in the gallery.

Inverting the gallery and bringing Australian art downstairs and moving international art upstairs marks an important milestone in the reconceptualisation of the national art collection.