Service accommodation will always be available because we couldn't post a family from, let's say Scotland to London and expect them to pick up the bill for the move (minus the first 5k) and the substantial difference in house costs. Servicemen will be UNABLE to move and therefore the situation is untenable.
Affirmatron, you're right; but the gist of it was that if you can't afford to move your family it's the same as choosing not to move your family. From what I understood, if I'm posted from Scotland to London then I have to accept that my family will stay in Scotland while I live in for the duration of my tour.
The idea appears to be that most spouses would have their own careers and not want to move, while the money saved from not providing quarters would improve messes, making them more pleasant places to spend 3 years.
It is, of course, completely wrong, and not what ANYONE in their right mind would want. It also doesn't consider those of us smart enough to marry a teacher, or someone else who can work in most parts of the UK; nor does it consider that maybe we'd all prefer to live together with our families?