I have become a work of art..

..and I have a certificate to prove it.

As part of this year's Frieze Art Fair, Gavin Turk brought his "Bikes de Bois Rond" to Regent's Park. The bikes are sturdy three-speed models, the frame wrapped in a decorative cladding in a style borrowed from a Polish artist. A brief escorted ride around the park's Outer Circle, past the Rose Garden and the back end of the Open Air Theatre, costs a mere penny charged to a credit card, though anyone absconding with one of these colourful machines would find a charge of £5000 appearing pretty soon. That you can indeed spend a penny and call it art these days may, no doubt, be an additional hommage, to Duchamp.

On return, a tear-off slip confirms that I am "to be considered an authentic work of art for all intents and purposes". Don't all genuflect at once.

This was just one of the exhibits in the open air Sculpture Park, a scattering of sculptures and installations in the English Garden (looking splendid in the autumn sun). This part of the fair was at least free: I didn't bother with the exhibition marquee, which cost a cool £25 (I may have been certified, but I'm not that certifiable). It was enough to enjoy the return of the sunshine and wander through the collection, which included what looked like dilapidated statues of Darwin, a distorting mirror that swang this way and that in the breeze, a couple of stone eggs, a maze made of water hyacinth root, and an elevated pile of German rubbish (literally) complete with smoke and sound effects.