Happy to report, that yesterday I removed the input euro plug and replaced it with a UK 13 amp, wired it blue, brown, etc as normal.
Attached a new euro plug to my mitre saw wired brown/blue etc and the same with the vac. Plugged them into their respective slots and Lo and Behold ... no sparks or smoke.
The vac starts a second or so after the saw and runs on for a few seconds after.
Forgot to say I previously repaired the vac (loose motor wire)
So now its all tickety boo