Gonzo is correct - the sub-roster is a dream, 4 days a week (or 28 hours), no weekends, and the potential to work at least 4 AAVA's a month for at least £2000 extra before tax - and there are 10 people/month doing that!
Looking at that a different way, those 10 people COULD be working 400 hours/month, a difference of 120 hours or 3 ATCO's! Don't knock it guys!