Thank you for all of your replies

I took Louis to a local companion dog show today and I dosed him up with some chamomile tea first, then a couple of drops of Rescue Remedy when we got there

. I can't say for sure that they worked, or if it was just the heat, but he was a lot calmer than I expected.
The show was the 5th annual one run by the training club that I go to and I think it's outgrown the venue. You couldn't move an inch without having to walk past all sorts of dogs and Louis was one of 50+ in "Most Handsome Dog" and hemmed in between 2 big dogs in the ring. On his way in a little black hairy terrier leapt up from under a chair and snapped and snarled at him but he didn't retaliate

We didn't get any rosettes today but I'm really pleased

that he coped quite well with being so close to so many dogs and with so much noise going on. I let him say hello to a few friendly dogs that I know and he said hello briefly to several more as we walked through the crowds. We found a quiet, shady corner of the car park as a refuge to give him some peace between classes and that helped too.
It was a small step forward for Louis but an important one after his anxiety and reactive aggression with other dogs since being attacked a few weeks ago. Tomorrow we've got a Kennel Club Show, but it will be less crowded than today and we won't be there very long, so fingers crossed he'll stay calm tomorrow and carry on gaining confidence.