We spotted quite a large swarm in our neighbors field yesterday. It was probably from one of our hives; we were expecting it to swarm because we found it with capped queen cells over the weekend. This was a result of not being able to check them for a week because of the poor weather, allowing 13 days between checks.
The swarm had attached itself to a small blackthorn sapling that had keeled over under the weight. It was really simply to cut this at ground level and lift the whole swarm over the 'nuc' box and shake the bulk in.
The remaining bees then walked calmly into the box - totally fascinating to watch.