Thanks Rip. I agree, he's done really well on many aspects he is vastly improved on how he behaved when he first arrived. I am introducing the whistle at the recall workshop on Saturday. I had always intended to put the most important commands (recall and emergency stop) on whistle. I've owned the whistle for ages but have never actually done it, but I will do. His emergency stop is a bit reluctant. He stops and veeeeery slowly sinks to the ground in his own time but I'd rather he went into a down to stop him creeping forward. More work needed on that, I'll look at your method.

I was going to suggest training a stop for those high-temptation situations too, might be easier for him than a full recall.
Don't know if you would be better off introducing the whistle now, at home? One method I've heard is to blow the whistle for dinner time (preferably if he's in another room though I know my two are glued to my feet when they hear the dinner bowls being picked up ) so they learn whistle = meal, as a basis.
I tried to find the guy I bought my longlines off on Ebay but his shop is closed at the moment (says he's away), there are some 50' lines on there by others for about £7 though.

Problem with training the recall at home is that he NEVER leaves me alone! He's constantly under foot I either have to get mum to hold his collar, or put him in a Sit/Wait. I'll introduce it around dinner time though. Yes I do want s long long line. I'll look on eBay. Maybe I can inspect yours?

I'll be using one when we next walk so feel free to inspect They're nothing fancy, but they're doing the job. Lightweight enough to carry around when road-walking, mine are only 30' though, but rolled up it fits into one of the big pockets on my walking coat. Do give a nasty rope burn as I found out but with gloves (and long trousers!) you should be fine. I saw a link for some bungee lead attachments the other day too, you clip a normal lead onto it then clip the bungee bit onto the collar, takes a little bit of the force out if the dog bolts to the end, might be worth looking at (though not sure if it would take them much force out of a 50' run up!)

Have a look at some gundog training sites for some tips on training the stop command using a whistle. Everyone does it differently so it might be a good idea to find the one that suits you and Cain the best. I always start off by doing some lead walking and blowing the whistle, asking the dog to sit and then giving a treat/reward. Once they have got the hang of this then I start to train it in the house and garden leading to training it out on walks with more distractions. Another way is to blow the whistle and make the dog sit before it's given it's dinner, that way the dog learns good associations with being asked to sit/stop.