After 2 days my OH came in with a grin, "come and see what I found!" and won my heart again. There, lying on the ground, about 20m from the hive (a topbar hive) was a mass of brown/yellow. Good tip darkbrowneggs, thank you. I must have walked right past them last night, but I was looking upwards and listening hard. Actually they were not making any noise at all when we found them.
I have never seen a swarm before, but heard a lot about them. Veil, gloves and boots on, box and tried to get them into a box. Being on the ground this not so easy, ended up ripping up the nettles they were sitting on/under/around up and putting the lot into the box. At first they were really calm, but the ripping did not please them. Good thing the gloves were thick. Rain started, closed up most of box and went for dinner. When I came back the stragglers had gone into the box (so I'm thinking the Queen is in the box) and I tipped it into the unsued end of the topbar hive. First I put some of the newly drawn comb (which they made before they swarmed) into their end of the hive, to encourage them to stay. There are some nettles in with them now, so will have to go in in a few days to make sure they don't get built into the new comb I'm hoping they're going to make.
Tonight I am feeling high. Bees are just so wonderful. My 9yr old daughter, on the pic., as I put her to bed said "I love the bees Daddy" and I agree. They are just so different from other life forms, and so interesting (if not cuddly).
The next thing to do will be to check they settle in the new end of the tbh and check out what VEG had to say about avoiding cast swarms.
Thanks everyone.