Cannabis farmers?

[TopTree]

Was anyone arrested or did the Police tip them off before the raid.

[ratty]

It's very unusual for any arrests to be made in a cannabis farm. The attendees only need to be on the premises a couple of hours a week, so unless plod get lucky they will not raid when anyone's there.

Staking out these place costs a fortune and therfore does not happen.

Usually the attndee is some poor illegal immigrant anyway who would not dare "grass" on the owners.

[LondonMix]

The press reports suggest over 100 people across London were arrested during the coordinated raid and that they believe they are dealing with a Chinese or Vietnamese gang.