Monday The first sighting is mid-morning. Scrawny, dark-haired and ambling past Year 3, it provides a welcome distraction from maths. The NQT refuses to do break duty with a strange mongrel roaming the grounds, but it's doggie who's in more danger - of being patted to death by 200 small hands. We use the head's sandwiches to try to lure it to the main gates. Then the bell rings. A tide of five-year-olds proves overwhelming, and the dog scarpers.
Clearing out the Free Books for Schools crisp crate produces 500 tokens and an assortment of mouse droppings.
Tuesday The car park has a surreal air, with a carthorse planted in the middle of the Tarmac, defying flashing lights and car horns. The stray horse department at Central Office sounds resigned, "Oh, it's with you now, is it?".
The canine interloper returns, and the parents are voluble: it bullies a chihuahua, sniffs an alsatian's bottom and tries to mount a pedigree spaniel. Well, that's what dogs do.
The rat man sets up shop.
WEDNESday Dobbin's chum joins him. Central Office has tracked down the owner, who isn't in any hurry to shorten the equine holiday. The horses ramble through our millennium forest, beg treats from passers-by and snooze in the caretaker's garden. By lunchtime two piebald bottoms are jockeying for position in the kitchen gateway as their front ends gorge bolognese from the swill bins.
A parent reports seeing a mouse streaking though the office. I reassure her that the rat man is already dealing with it, then realise she is joking. I pretend I'm joking too.
THURSday Call Central Office again as the horses are becoming a permanent feature. Parents troop in to complain about manure in the playground. Children gather round, inspecting the heaps. By break, Year 4 will be kicking the stuff at one another. The nags spend the rest of the day in the forest, nibbling saplings and scratching their rumps on the stakes. The head wonders if the budget will run to installing a cattle grid.
FRIday Tomorrow's summer fair may have to be cancelled. Three more horses appear, and they all surround the kitchen. The cook refuses to throw out the slops and threatens to call the SAS. The rat man removes a handful of rodent bodies. By 3.30 the millennium forest is reduced to splinters and the horses are splashing happily in the pond. At last someone has a bright idea. Give the fair a Wild West theme, incorporate the horses and we could have our own rodeo - 50p to ride the bucking bronco anyone?
Frankie Searle is a school secretary. She writes under a pseudonym