If you tune in to today’s new Doctor Who special – and you should – you’ll be seeing it at the same time as everyone watching it anywhere it’s televised on the planet. That, in itself, is pretty special. And so is this new show, which somehow manages to pair the current Doctor, played by Matt Smith, with his immediate predecessor, played by David Tennant. Confusing? Yes. Entertaining. Ever since this series was revived from dormancy in 2005, absolutely.