This morning, a free-thinker in the vast organic dairy herd that live opposite us pushed her way through a gap in the hedge and found herself alone in an enormous field that was usually off-limits. Cows are nothing if not gregarious, so she speedily shared the news with her sisters and soon the whole herd was squeezing through the gap and spreading out into the field beyond. There was a majestic, remorseless, unstoppable quality about the mass break-out that reminded me of a lava flow. A black-and-white lava flow that mooed – the girls were excited, and said so. After a few minutes of milling about and getting the feel of the place, some of the younger element tried a few dance steps. A buck here, and a ponderous jump there and then the entire herd were getting on down and grooving in a manner completely at odds with their normal sedate behaviour. After their spontaneous rave they obviously decided to do the thing properly and have a grand day out, so they strung out in a merry line and headed out across the field towards previously undreamed-of new horizons. But then their equivalent of the riot police turned up, in the shape of the farmer in his ancient land rover. He was no fun at all, and all too soon he had gathered them up and they were filing bashfully back through their gap in the hedge, to get back down to their primary job of milk-making while the farmer did some emergency fence repairs. I walked the dogs through the cow field later on that day. They were all lying down and chewing the cud, but I thought I could detect a glint in their normally peaceful eyes. As parties go it was a short one, yet it should give them something fun to think about for weeks to come.