I squatted for a period in the early millennium, when I had no money and nowhere to live; and the house needed to be occupied at all times, or the landlord could reclaim it. We had a section 6 notice up outside the front door and everyone had to coordinate their movements so that there was always someone in the squat. It's not difficult, you just need to get in without forcing entry (open window etc), then you keep it occupied and put up a section 6 notice outside.

If the landlord came round and there was no one there, section 6 no longer applied and he could reclaim the squat without any legal ramifications. The government got rid of people's right to squat in residential addresses in 2012, but generally speaking, if you leave a squat unoccupied, you've lost your rights.

If you do everything by the book, then the landlord has to apply for an eviction notice, which takes time. Some landlords don't even mind so much, because they'd rather it was occupied by reasonably ok people, as opposed to drug addicts; (I helped clean an abandoned junkies' squat once because the landlord said we could stay there if we looked after it, it was so grim I can't even tell you.)

This woman would have to have been protected by some other means, I'm sure there are laws to limit this kind of thing from happening, but squatter's rights almost certainly wouldn't have been one of them.