THERE is a very particular thrill to writing site-specific drama. Places throw up stories of their own; characters put themselves forward for invention; the pictures in your head are real. The Bramcote Nativity almost wrote itself, suggested by the Victorian churchyard, the pub garden, the leafy hillside in the local park, and the Saxon church tower in the village which loving hands have restored.

An American strayed into the play when we first performed it in 2011, not knowing at all whether people would turn out in the middle of winter to tramp the streets and the fields. He blogged of crossing a real horse field with real horse droppings, and of a life-sized sheep puppet more real than anything he had seen: a comment that well expresses the sense of magic which can come from performing outside and being caught up in a journey, a shared experience for actors and audience.

The nativity story is thin: just bare bones really, and that's why it is so attractive to painters and dramatists. Provided you don't stray from the essence of the Gospel accounts, you can speculate and elaborate and imagine who, aside from the main characters, might have been there and how their lives might have been interrupted by the momentous events that took place.

It's a rich field to plunder.

I studied some of the great nativity paintings, and what I loved in many of them was the curiosity of passers-by and the way people are depicted piling into Bethlehem. In Domenico Ghirlandaio's Adoration of the Shepherds, the elevated road in the background is full of hurrying horses and people; in Hieronymus Bosch's The Adoration of the Magi, they've scrambled on to the stable roof and are peeping round corners. In Benozzo Gozzoli's Procession of the Young King, the rocky road is crammed with travellers and flanked by leaping animals, and in Rubens's The Adoration of the Magi, heads are peeping over heads in the queue.

So the mind ferments. I wanted the play to be akin to the Mysteries in its robustness and irreverence, and English, as though a bunch of people in the Middle Ages had got together to tell the story. I speculated about the Census: how the travellers would have grumbled at having to journey so far, getting blisters and resenting the Romans and hating Caesar Augustus and Herod for forcing them to interrupt their lives. Into this mêlée of muttering people would arrive the pregnant Mary and anxious Joseph, fearing the consequences of having to wait in the queue while unfamiliar labour was beginning to rumble.

And then there's the Inn. It would be full of travellers, of course - no hope even of a late booking - but what if there was something else going on there as well, some kind of a "do" to compound the problem and cause added vexation? A betrothal perhaps, with arriving guests and a bit of a party and a dance in the garden before Mary and Joseph turn up with their ridiculous request for a room.

On then to the Shepherds Fields, where a fire can be crackling and a lambing awaited, and shepherds can grumble about their lot, and you hope for a mist out of which the Angel Gabriel can appear, or for a burst of sunlight to catch the shimmer of his wings. And then via a leafy, mossy lane to the Stable itself, the bafflement of residents why all these people are crowding in and babbling about babies, the colourful procession of the Magi, and the hurrying feet. When Gaudete is sung, with lustiness rather than refinement, it should set the place alight and herald Christmas.

Promenade plays are not for wimps. The logistics of setting up four different scenes in four different locations, keeping actors and audience constantly on the move, and protecting the early instruments of the processional medieval band if it should rain are just some of the things to keep a producer awake at night.

There are meetings with the police (incredibly helpful and supportive) and with the local council (ditto), so that paths can be cleared and locked gates opened and closed, and places and people made safe. There are hay bales to be begged from a farmer, lavender and rosemary to be cut and stored, apple to be piled into barrels. The stage manager is building brushwood dwellings in his garage, and the WI is making the Angel's robes.

And there is no self-indulgence for the writer: audiences need no long speeches and plenty of brisk action if they are to stand in the cold. Actors and singers have no amplification and have to compete with whatever sounds are around them. But a nativity, like a Passion play, speaks for itself, captures the imagination, is timeless in its appeal and its integrity. Bosch's painting depicts a face flattened to a torn gap in the plaster of the dwelling to see what's going on. That's the curiosity and that's the wonder of it all.

Star Safari, The Bramcote Nativity, is on Saturday 13, Sunday 14, and Saturday 20 December, at 11 a.m. and 2 p.m. each day. Tickets and information at www.bramcote.info.