Hmmmmm,
Having never claimed it during my time I won't even pretend to know much eligibility and claiming it but I did used to wonder sometimes how people got it- I worked with a spec aircrew (or whatever they are called now) Sqn Ldr who claimed it for his 3 kids who had done 3 consecutive tours at the same station (but different units on the station) and had no chance of being posted anywhere else. Pretty sure the kids were at a school close enough to his home that they could have been taken daily.
There's always going to be loopholes- at the same unit I worked with 4 guys who all lived 30 miles from the station, all were on days permanently so they car shared but they all claimed 60 miles home to duty every day!