Peter Freeman

This remains one of the finest productions the BBC ever made. Alec Guinness is superb as Smiley, secretly brought out of retirement and tasked with identifying the highly-placed Soviet agent who has been working for years to undermine the Circus (MI6) and betray its agents and its secrets to the Russians. The plot is labyrinthine, the pace is slow, events gradually unfold over seven episodes until the traitor is unmasked. Anyone weaned on fast-paced shoot-em-up crime or spy dramas is going to be mystified by all this, but that's their loss. It was, at the time, absolutely essential viewing and John le Carre himself rated it as his favourite adaptation of one of his works. It's a five-star masterpiece and I would love to sit through all of it all over again. The 2011 Gary Oldman film version is quite good, perhaps, but this is the original and the best.