How to describe a happening of this sort? Burford Biennale would be good, for time but not for place: we're a couple of miles short of that delectable Cotswold spot where it's always teatime. How about Asthall Assembly? That's better. The place is beautiful Asthall Manor and its gardens where every two years Rosie Pearson lets her sculptor friends dispose their creations. And Assembly' has the hint of elegant riot evocative of those former occupants, the Mitford Girls.

This is the third of Rosie's exhibitions, and as full of pleasures and surprises as ever. There are 14 artists and more than 50 major works, some eye-catchingly displayed, others met almost casually along paths and under trees. Keep on the Grass' should be the sign here that is, keep off the flowery banks and slopes. A natural' garden takes a lot of creating, and meadow flowers have to be planted. Rosie's chief accomplice is gardener Mark Edwards, who makes his own green sculpture a sinuous curving bank framing Peter Randall-Page's granite Secret Life. There are old-timers here, and some new boys (and girls). The latter includes Richard Aumonier, who specialises in magnificent pieces in highly-polished granite quite spectacular, using the great range of this rock's natural colour in narrow bands. More amazingly stlll, he tells me much of this beautiful material is off-cuts from posh kitchens and worktops, destined perhaps for Mick's Skips. Another newcomer is Emily Young, also with a penchant for expensive materials in her case chalcedony, used for two huge discs (on the terrace and in the ballroom) which glow in slanting sun. She carves heads too, in Purbeck marble, dignified and commanding, as in Warrior Poet. A third, Emma Maiden, works on a smaller scale. Her variations on Madonna and child are disposed quietly about the garden.

Among the old-timers, Luke Dickinson introduces the show with a fine piece in Indian marble whose title must speak for itself Summit Lust. Many pieces, indeed are worked in exotic stones, which the artists have travelled to choose on the ground' as it were. Paul Vanstone, told me he had travelled to India for the Rajastan marble whose red and brown veining works mysteriously through his paired figures, and for the striking Himalayan marble in the imposingly-moulded torso Man Mountain. Anthony Turner is a familiar Asthallian. He has a special bower made for his tricky Seedsown in Humblestone a two-piece which can (just) be moved to emit a growly sound, but in the ballroom he has a whole tableful of smaller intriguing shapes of seedpods, acorns what he calls his "Jungle Floor Bonanza". Emily Young has some highly-polished alabaster pieces here, too, while in the cloister' outside is Jon Edgar's Wight Man which is, I'm told, the last piece of Derbyshire alabaster.

All these are rightly called works', representing long hours of struggle with unyielding stone to find its secret shape Young's Warrior Poet, for instance took 100 hours of polishing, and Vanstone's Leaning Orator nonchalantly wears a formidably draped robe. No holiday for the artists but a fine afternoon out for us. And don't forget tea in Burford. Till July 9, open Wednesday to Sunday, noon-6pm.