Iwould be failing in a duty to an old friend — to several old friends — if I were not to mention the various ancillary events arranged to add further lustre to what is already one of the shining beacons of the county’s cultural life, the biennial on form exhibition of outdoor sculpture in the lovely grounds of Asthall Manor, near Burford.

The month-long run of on form 14, between June 8 and July 6, is punctuated throughout by talks, demonstrations and performances. The proliferation of these has led some to wonder at a change of artistic policy, but the event’s founder and co-curator Rosie Pearson says this is not the case.

“We are not ‘turning into a festival’, as somebody suggested,” she told me. “We are just subtly adding in a few extra bits and pieces to enhance the experience without detracting from the sculpture.”

This is not, as I misleadingly said at the start, outdoor sculpture exclusively. Some pieces are also displayed in the ballroom, which was added to the 17th-century manor house by Lord Redesdale, the father of the celebrated Mitford sisters, who lived there in the 1920s. There are others to be seen in St Nicholas Church next door.

The defining characteristic of all the work is that it is executed in stone. On form is the UK’s only show dedicated exclusively to this. It had its origins in Rosie’s commissioning from sculptor Anthony Turner of two finials to adorn the manor gateposts. The stir created by the installation of these curvaceous organic forms led them to wonder what would happen if the lovely garden at Asthall was filled with other striking works in stone.

What happened in 2002 (when, in fact, the ‘stone only’ rule had yet to be applied) was that ten artists contributed 56 sculptures, which were admired by about one thousand visitors. This year, by contrast, there are to be 30 sculptors showing nearly 200 works. After free admission in the first year, a charge of £5 was levied, rising in 2012 to £7.50, which is to be held this year.

Rosie tells me: “Our aim is to make money for the artists, to cover our costs and pay for some of the upkeep of this historic house and garden, and also to spread joy. I am the sort of person who gets — not bored, but who starts looking around a bit once I have done something successfully.

“I adore stone sculpture, but it has come into my life entirely by accident. My first loves are literature and theatre. I am also passionate about generosity and friendliness and trust and nature. So I thought to myself, why not use the goodwill that this exhibition has generated to cross some bridges, and just subtly take people (including myself) in directions they might not have thought of. The extra events and so on have emerged organically, mainly from conversations and unexpected connections that my collaborator Anna Greenacre and I have had.”

One extra event that I intend not to miss is the talk at 2pm on Wednesday, June 11, entitled The Call of the Wild. Rose nurseryman Robert Mattock, an old pal of mine, will discuss the influence of the Broadway Group of artists, which included John Singer Sargent and Alfred Parsons, on the movement from ‘formal’ to ‘wild gardening’ in the Cotswolds. The talk will be followed by a walk around the garden with Robert and the manor’s head gardener, Mark Edwards, focusing on the fine range of roses at Asthall.

On Fridays June 13, 20 and 27 from (10am-4pm) artist Francesca Shakespeare is hosting painting workshops, and on Saturdays June 14 and 21, from 2-4pm, there are children’s carving workshops with sculptor Aly Brown.

On Saturday June 15 and Friday June 20, at 3pm, there are geology tours led by Philip Powell, the Honorary Associate Curator of the Oxford University Museum of Natural History, looking at the diverse stones at on form, the fossils within them and other signs of their great history and age.

On Saturday, June 15, at 5pm the Lower Windrush Choral Society is is giving a concert in St Nicholas Church.

On Wednesday and Thursday June 18 and 19 June, at various times during the afternoon, there are to be stone balancing demonstrations by Adrian Gray On Wednesday June 25 at 6.15pm (£15, booking essential) students from the Oxford School of Drama are giving an open-air performance of William Shakespeare’s A Midsummer Night’s Dream. As one who has known the school since its earliest days, I feel confident this will be a splendid show. The students are also performing scenes from Shakespeare’s Pericles at noon on Thursday, July 3.

The next day, at 3pm, there is an opportunity to talk to Isabel Bannerman, one half of the Bannerman design team that created Asthall Manor’s garden in 1998. On show will be Isabel’s extraordinary large-scale photographs of plants, exploring the architectural and ‘engineered’ aspects of the plant kingdom — so important to her own design process as a garden designer.

There is more drama that evening between 6 and 9pm, as groups leave every 20 minutes on a event from Scary Little Girls called The Ghosts in the Stones, inspired by the history of Asthall Manor and on form. This will feature the work of such writers as Aphra Behn, Andrew Marvell, George Eliot, E. Nesbit, Wilfred Owen and Nancy Mitford.

Full information on all these events, and more, can be found on on form’s excellent website (onformsculpture.co.uk).