Nomad (who ISTR is from Scotland) may have better info, but its worth remembering that the law is different there.
The Scots do not permit the “squatters rights” legal loophole that is used in England and Wales to occupy land or buildings prior to holding a party.
In Scotland, all forms of trespass are a criminal offence and the Police can immediately arrest some1 who is found in some1 elses property even if it is disused or empty.
This may well be a factor which accounts for the lack of underground events in Scotland; another (lesser)? issue are “neds” or troublemakers who disrupt otherwise peaceful gatherings (but we do of course get these in England as well!)
