Jamming equipment is illegal to use in the UK as it violates section 8 of the 2006 Wireless Telegraphy Act.

Somebody tell whichever agency of the state it is that jams mobile signals around the Eurotunnel terminal, then.

A lot of Turkish buses have two cirular logos sandblasted into the windows - a fag packet and a mobile phone, both scored with "don't" lines. Both bans work. The only time I've heard anyone use their mobile on a Turkish bus, they were directing the emergency services to a major crash.