Hi Jukes mum - it's horrible isn't it. I went through the exact same thing a week or so ago - 7 hens and a cockerel killed in the middle of the day, torn apart bodies strewn about..... Our hens too are totally free range during the day, and locked tight in their houses at night.
In the immediate aftermath of the attack, we changed what time we let the survivors (3 hens and the old cock) out in the morning. It used to be the very first thing my husband did on going out, but now we leave them until about ten. Initially I stayed around in that area the whole time they were out, except for lunchtime. We found that we could tempt them to bed by feeding them their small handful of scattered grain inside their shed (fairly large - garden shed sized). They won't go in if we're watching, so we put in the grain then go and do something else for a short while and we come back to find them all pecking away, so we shut the pophole and they're safe for another night. Last night they were in by six, and it's usually seven. Previously they wouldn't go in until the last gasp of daylight for most of the year, but about 9 or 10 in the summer.
We're a bit resigned to the fact that the remaining birds will probably be taken at some point, but meanwhile I intend to fight it. The worst time is right now when the young foxes are being taught to hunt, so they start off with something easy. Our hens wouldn't have run off as they're used to dogs around the place. The fox which got them looked fairly young to me, but I was so surprised it was hanging around that I didn't look closely.
I think for getting them to bed early, you just have to persevere with lifting them into their house every evening. If you leave them out, then come first light they'll hop down off their gate and it's foxy breakfast (been there). They should get used to being fed some grain inside though. We were surprised at how quickly ours got the message.
By the by, one of our hens had gone broody the day of the attack (how she survived I think) so we popped the last half dozen eggs from the flock under her, while they were still laying fertile eggs (the old cock is now infertile) She's still sitting tight and the eggs should hatch mid July

so there's something good to look forward to
