There is no exhibition comparable to FREE at the Southbank Centre, which is the UK's annual national showcase of arts by prisoners, offenders on community sentences, secure psychiatric patients and immigration detainees. You will have never seen an exhibition like this. I certainly hadn't and I was intrigued and surprised by this show that marks the 50th anniversary of the Koestler Trust, the UK's best-known prison arts charity. 

The sheer range of 58 art forms displayed in the exhibition at the Spirit Level of the Royal Festival Hall is impressive. FREE consists of artwork including paintings, drawings, craft works, sculpture, music, film and writing. Artist-turned-curator Sarah Lucas (of Young British Artists fame) designed the exhibition and selected work from over 8,000 entries, which she whittled down to 180 pieces.

In a video about her journey curating the show, Lucas states that her choice of grey breeze blocks as an exhibiting tool and design feature was not made because of its obvious connotations of prison architecture and atmosphere, but that she uses breeze blocks frequently in her own work. However, the viewer cannot help but make that visual connection, especially when the blocks are twinned with toilets used as holders for headphones in the sound work portion of the exhibition.

In a separate exhibition area is a square-shaped raised plinth made from breeze blocks. Here, the harsh grey material of the breeze blocks is echoed by the concrete of the other Southbank Centre buildings, which are visible through the window behind the exhibition platform and which play on the idea of being inside versus outside.

In the main exhibition space, the many paintings line the walls of the main gallery space. All of the paintings are unframed, which was an interesting curatorial decision on the part of Lucas. These paintings mostly depict faces, which creates a haunting effect as the viewer walks down the gallery, where a long plinth is positioned in the centre on which sculptural and crafted pieces stand.

For me, the craft work pieces were the most effective, beautiful and demonstrated the highest level of skill and effort out of all the works in the exhibition. For example, a piece created through matchstick modelling, which must have taken hours of dedication and ability to achieve, or a ring in the shape of a flower made of recycled pencil sharpenings is so detailed and delicate. Many of the ceramics and sculptural pieces appear to be absolutely professional and worthy of displaying alongside work in galleries for contemporary craft work. The textile pieces, including bags and cushions, were sometimes humorous and always exact in their making.

Exhibition visitors are able to vote for their favourite artworks and include comments, and the artists who have made the works will read these - a process which furthers this dialogue between those who are free and those who are 'inside'. Another way this sort of dialogue is fostered is by the ex-offender interns, specially recruited by the Koestler Trust. They have been trained in collaboration with Southbank Centre, and lead the exhibition tours - and are all older than the Trust itself. 

In the back of the booklet accompanying the exhibition are comments from some of the artists on their exhibited work. The winner of the Kate Massey-Chase Commended Award for Drawing who exhibited The Moment from HM Prison Parkhurst, wrote "I wanted people to know that any form of artwork can be created anywhere by anyone and ... change people's lives ... by inspiring them ... in some way that will make their world a better place to be." This quotation demonstrates the immense power of art and what creating it can do for people, whatever circumstances they find themselves in. I found that this exhibition gives visitors a view into another world, just as the act of making art for these imprisoned or institutionalised people gave them a window into the world outside.

Not all of the artists whose work is exhibited have committed a crime. Yet none of them are free. It seems that ''doing time'' allows for focus and time to be dedicated to achieve incredible results with art. The exhibits are not naïve art, but of raw and high quality: FREE is an exhibition of true Outsider Art.

Free: Art by Offenders, Secure Patients and Detainees, at Royal Festival HallKate Eleanor Ross reviews Free: Art by Offenders, Secure Patients and Detainees at the Hayward Gallery, Southbank.3