Well I never!

http://www.guardian.co.uk/world/2010/aug/17/drugs-trade-drugs

"Between 2004 and 2007, 800 cannabis factories a year were being
uncovered by the police," Gibson said. "That rose to over 3,000 a year
in 2007-08 and over 6,800 in 2009-10. This increase is attributed to a
number of factors, including an increased focus on law enforcement."

So what were the police doing in the meantime then?

 

Sensible people use basements and generators but to be really safe you need
to vent the hot air in a non suspicious way.
It must be rather fun flying around with a FOAD infra red camera and it's
obviously rather effective.

 

Heh. One bunch of Chinks in NI tried doing it in a carry out, thinking it
would mask the emissions. Nil Points.

A smart operation would run a pipe to a neighbouring stream, a few feet
running in the water then venting under water. Apparently.

Or just put it up the Falls Road, pay yer dues to Provo and Plod won't ever
come near.