Threadneedle Prize for Painting and Sculpture, Mall Galleries, London

The Threedneedle Prize is an open competition, now in its fourth year, for painters and sculptors working in the representational tradition in the UK, with a hefty first prize for the best piece in the show of £25,000. On top of that, visitors can vote for their own favourite quite independently of the three judges. That could win the same lucky person an additional £10,000, which adds up to £35,000 in all. Wowee.

The show itself is at the Mall Galleries, which are beginning to look better than they have ever looked. I choose that word "beginning" quite carefully, because there is a way still to go yet. The main space is divided into three areas, the main exhibiting area to the left, a central area for the reception desk and book shop, and a bit of exhibition space to the right, which looks and feels very unsatisfactory. There are a couple of additional galleries off to the back of the principal exhibition area too, with both look and feel like a gloomy afterthought, making visitors feel slightly sorry for those artists who have to show there.

Having said all that, Threadneedle 2011 itself looks better overall this year than ever before. The work is more discriminatingly chosen than in the recent past, being generally of a good standard, and this time there are fewer objects to crowd the eye. Representational art is a broad church. What we find here, for the most part, are variations upon the idea of landscape and variations upon the idea of portraiture. How do you vary portraiture? You blur the human image, you cut it up into bits, you muddy it, you fracture it in different ways, you paint it in part – or you paint just bits of the body, and let them float free of each other. Eerie stuff.

These tricks of the modern figurative trade appear and re-appear throughout the show. Having said that, the very best painting in the show scarcely resorts to modish trickery at all. It is called Gallery Woman 2 and it is the work of the Sussex-based artist, Tom Hammick. We see a female gallery visitor from behind, looking at a blue painting. What is so wonderful about this painting is the use of colour. Hammick's manipulation of blue, his massaging of it into the picture space, gives the work an extraordinary lift and coherence. It irradiates the space, raising us into a mood of concentrated appraisal. Which is the mood of this onlooker, we feel.

To 8 October (020 7930 6844)