The other week, a fire emergency system was accidentally activated at a broadcast centre in London, which caused Channel 4 and Channel 5, plus a number of other Freeview channels, to go off-air for about 30 minutes-or-so. In this digital age, such a lengthy blackout caused a few raised eyebrows, and a lot of tut-tutting amongst disgruntled viewers. Blank screens for 30 whole minutes! How dare they!