Thanks fellas. It was acute lymphoblastic leukaemia which did the damage. The vets advice was that I knew what I had to do. The chemo would have dragged it out and high probability that it would have killed him anyway, and without any action he would have suffered for another week. I am glad I was able to stop his suffering and keep his dignity.
The support from people on this site via text, phone calls and PM's has been awesome.
We are enjoying the holiday, and spending time with our other 5 dogs - but the Jetman is not far from my thoughts. Some great memories.