I always do do the blocking technique

We have been back to training classes since I started this thread, and in class there are 3 labs that he does not like, 1 in particular he despises. I now have got to the point where he will ignore them and actually work in their company, and touch wood, we haven't had an incident out and about since, so think we may have nipped it in the bud.
We also reinforced who is boss. We had a new sofa so perfect opportunity to stop dogs getting on the furniture and stopping them getting on the bed, so the pecking order in our house has been restored with me and my OH being at the top again. Logan seems a much happier dog now, even if he initially didn't like not being able to get on the sofa!