Your husband was about right! Grades are just a salary range, for example;
Grade 1 = £10,000 to 12,500
Grade 2 = £12,500 to 14,000
Grade 3 = £14,000 to 15,500
and so on. Depending on the acceleration of your particular organisation, it can take a year to reach each spinal point (the salaries between those figures) In my public sector position, I have just reached the penultimate spinal point before I would have to be re-graded (which usually involves promotion).
So, lets say you have the experience for Grade 3, the company wants to get you at the 14 k mark, but your experience might make a good case for a mid-range of something like £14,8 or £15k) Most public sector jobs begin at the lowest spinal point within each grade.
I hope that makes sense!! I can only get one more pay rise next year until I have to be re-graded or the only raise I would get every year would be a union-negotiated cost of living raise (ie: peanuts)