When I take her outside now, she's getting to be really good - doing her business within five minutes, and only a little messing around before she follows me back in. longpig's still having more trouble - I don't know if we're doing something different from each other, or whether it's just that Hazel has her all day and Ginger's just acting up more with her. It probably also doesn't help that during the day there's more to be distracted by, and it might just be that this evening was the first time she really felt the front lawn was the "right place" for the toilet - I accidentally trained her initially that it was the back garden, before Hazel pointed out that our neighbours' kids would be playing there.
I've just put her to bed for the night, and she went without any fuss. She didn't need as much playing either - it's probably partly the heat, but she just wanted some help chewing her bone (she's been chew-crazy today) and she climbed into my lap a couple of times for a cuddle/stroke/sleep before I put her away.
A lot of people have been recommending some very effective-sounding punishments to us, which is really helpful of them, but I've never felt that a dog needed to be punished in order to learn, so long as you can be strong enough not to react to them when they're being bad. The closest we're getting to punishing it to "dominate" her when she's doing something she has to stop immediately - holding her on her back with gentle pressure on her chest, and meeting her gaze until she looks away, then letting her go. It's only worth doing if you can turn her over while you're pulling her away from what she's doing, but it's been really effective - she walks away after, and then comes straight back and is very affectionate - licking and gently climbing onto my legs if I'm sitting on the floor.
Right - best get some sleep myself!
[ETA] I'm not strongly against punishment as a dog-training tool - especially as the punishments suggested aren't harmful to the dog. I just never had a taste for it, and I find positive reinforcement very effective.