We ought to have known, really. If there is anything early Saturday evening television has taught us, it's that whenever something is amiss in major British cities, it's got something to do with a Time Lord.

The following copy has just arrived down the wires from Cardiff:

Two controlled explosions will be carried out in Cardiff this afternoon, as part of a BBC production, believed to be Doctor Who or Torchwood.

The explosions - large enough to damage a number of windows at the film site - will take place at 1200 and 1400.

South Wales Police say they understand that, with the heightened security measures currently in place across the country, this may cause some concern to members of the public in the vicinity who are unaware of these events.

High visibility uniformed Police Officers are on duty in the City Centre to provide the necessary public reassurance.

Quite what South Wales Police think those officers will achieve, God only knows. Have they not seen the show? You need a police box!