It's called democracy. If I remember rightly it was around an 80% turnout with a 68% in favour. I'm sure I'll be corrected if these figures are wildly inaccurate.
I don't for one minute believe that all of the present Band 5 ATCOs voted for it-indeed I didn't, just as I don't believe all of the other band ATCOs voted against what has been around a 35% rise in basic over 6 years.