@Thistle the dog, thanks for the information, good to know. We had another really good walk this morning with little pulling (!!); fortunately we have a bushy park directly opposite us and it's a very short, quiet walk to get there. A good chance to practice and he then gets the chance to run around off lead, which is another great reward.
@JRG, I agree that I wouldn't want him necessarily walking at heel all the time. I would be quite happy for him to walk on a loose lead, rather than heel, but at this stage if he's out front he can't seem to help himself with the nose down and pulling (of course, that's what he's bred for - not the pulling, but the nose work ). I did notice towards the end of our walk that he came to walk by my side naturally, off lead, which is great, but I probably will need to teach him a release command so that he knows when he can go ahead and "get on".