Oh, Before anyone says I could have used a reversed Irwin clamp as a spreader in the neck slot.
A reversed Irwin Clamp needs at least 75 mm wide space to get into. even the little 100mm Green shed one I have is well over 60mm wide.
I probably could have made something up out of a couple of bits of wood and some rope. But I like the way I went about it better.
PK