Hi Nicola, thanks ever so much for this advice - I hadn't considered chasing her before but will start to do this. At the moment I am too nervous to let her off, but might do at the weekend when OH can come with me.
We had a good walk this morning, I used the harness with Fern (which I haven't done since last season) and she was absolutely fine with it, and she walked like a dream (on the retractable lead). I was telling her to 'leave it' as soon as she picked up a scent, and kept saying walk nicely (which is our word for heal) and she was great. I kept her close on the walk down and on the way back up I had it loose and she walked to heal - good girl!
When we were coming back up the track there were about 5 pheasants in a gate way so we stopped and I said leave it and Fern sat, but then she tried to pull and I said no, leave it. Then she sat again. I said 'come on then' and she came along with me happily so got rewarded.
If she wasn't on the lead I am sure she would have chased, but I think if I carry on with this it has got to help.
Also my OH knows of somebody who trains gundogs, its just a case of tracking him down, and see if we can get some controlled training with game.
I am determined to crack this!