Thank you Karen, everything you have put makes sense, I am going to start from scratch with the whistle. Think I am going to use a tennis ball as that is one of his favorite toys and I think starting in the house or back garden is the way forward. When I am out on walks he is too interested in smelling the ground and just ignores me, he was never like that before, whenever I blew the whistle he would come running back, he is so good in every other way, you will have to keep your fingers crossed for me.