Per Kirkeby

Danish Pop, which isn't to be confused with the influenzally catchy chart fodder for which Scandinavia is famed, is, in the hands of Per Kirkeby, an erratic affair. 'Car Pictures' (1964-65), for example, are more like nature slowly reclaiming the wreckage of vehicles than incendiary collisions of content. Kirkeby - artist, writer, poet and former geologist - comes across as a landscape-inspired abstractionist, tempted by but sceptical of fashionable figuration. Or should that be compromised by it? Awkward impositions continue in this curious retrospective. From Pop we move to the New Image era, where Kirkeby paints a horse, tilting it a ludicrous angle in a sea of gestures that look like they really want to take centre stage.

In vast, relatively recent works like 'The Siege of Constantinople' (1995) - of fissure-like lines traversed by glowering forms that read as fractal lily pads - the pace is glacial, as if the artist was offering up doubt-filled correctives to Cy Twombly's floral comets. Kirkeby's small sculptures - of solemn buildings and body parts - are by contrast pacy and economical. It's as though something is dislodged through the application of oil to canvas that enables the artist to surge ahead in three dimensions. Does that make him a better sculptor than he is a painter?

The abiding impression is of a genuine grafter who displays flashes of brilliance. The show rings with arguments that take place in the artist's mind but it's also a reminder that we tend to like our greats more impervious to doubt, less encumbered by history. Kirkeby doesn't offer up easy answers, leaving us to pick through the strata of his thought processes. Once a geologist…