hi all reading the iva rules re front suspension the area between the arms is exempt from " sphere " test
I assume that include rear suspension would I be correct in this ?

Just had a read and it doesn't mention anywhere that it only relates to "front" suspension...just "suspension components". So it looks like the rears would be exempt in the same way.
If in doubt, fire an email off to vosa (errr, not vosa anymore are they, the dvsa). I found them to be pretty good at replying to emails asking for clarifications like this.