Since Mikeyboy built my special the rear shock has been a bit hard.
It turns out that if you spec a shock with the weight you want to be, not the weight you actually are, it doesn't work right.
After a few telephone conversations with John at Revs, he worked out that I needed a heavier spring for the larger gentleman. John packed it as he was on the phone and it arrived today. Brilliant service from Revs Racing. What's great about Revs, is that during several conversations, he talked me through everything I could do instead of spending money. In the end, I needed a new spring.
Also thanks to Mikeyboy and Magnon who swapped the spring over. It's completely transformed the back end and I now don't need to stand up all the time when I'm riding.