Most gardens aren't at all reasonable, preferring to sprout weeds and outgrow themselves rather than stay tidy and rational. However, the peace and quiet of Ham House's neatly clipped box hedges, cyclamen beds and well-tended cherry grove have been rudely disturbed by 17 artist-intruders, in celebration of the gardens' foundation in the seventeenth-century, the so-called age of reason.
That era's new-fangled Cartesian systems of geometry and Galilean theories of gravity inform the buoyant helium balloons and chalked line drawings by Ruth Proctor, which block the arches and span the lawns respectively. Similarly sensitive and synapse-firing are the disembodied voices booming from Kathleen Herbert's recorded sound piece, 'The Theatre of Flora'. Each voice speaks of the ills or gains of tulip mania, the rabid speculation in flower futures that led to a catastrophically burst bubble for the Dutch bulbs. (Sound familiar?)
Among the performative strands of this plein-air exhibition – a laudable exercise in audience interactivity for the usually risk-averse National Trust – is Harold Offeh's roving hermit cave, 'Arcadia Redesigned'. Apparently it was once on-trend to have just such an itinerant outsider installed in one's grounds, although perhaps a chirpy Ghanaian south Londoner dressed in rags might have been literally beyond the pale.
The more traditional sculptural style holds its own against the imposing backdrop of Ham House. Alexandre da Cunha's bright-red clamberable 'Compass', formed of ladders, and the cheeky dressing-down of classical statuary by Tom Dale, Simon Periton and Alan Kane strike the right note of irreverence for the country house setting. It doesn't all work: a video in the ice house and a topiary telescope wincingly titled 'Yew Tube' fall foul of cliché and clumsiness. But remember, this is not contemporary art's natural habitat. It's Richmond, the garden suburb of reason itself.