With the Cold War at it's height, the head of the British counter-espionage agency - "Control" (Alexander Knox) is giving a clear impression that he is losing the plot. He is visibly ailing so his subordinates gather like vultures waiting to take his place. His preferred candidate is the redoubtable, semi-retired, "Smiley" (Sir Alec Guinness) and pretty swiftly we discover that is because the old man is not so doting after all, and is suspicious that there is a spy in his midst. Who can he trust to investigate the matter? There were seven parts to this BBC drama and each episode delivers some more pieces in the jigsaw of his search for the truth and the mole. There's a fine assemblage of British character actors like Ian Bannen and Anthony Bate to populate the ranks of the helpful or the suspected - as well as the slightly odious "Esterhase" (Bernard Hepton), or the slimy "Haydon" (Ian Richardson) or the ambitious "Percy" (Michael Aldridge)! Indeed with such a breadth of promotion-hungry luminaries to chose from, "Smiley" and his right hand man "Guillam" (Michael Jayston) have no idea whom to trust as this cleverly crafted, internecine, story of betrayal and duplicity unravels before us. John Irwin and Arthur Hopcraft have developed John Le Carré's original novel thoroughly, with plenty attention to the detail. There are clues a-plenty, red herrings likewise, and the slow but punctilious process in which the traitor is sought is expertly delivered by a Guinness performance that, like the whole thing really, is engagingly short on extended pieces of dialogue concentrating more on immersing us in a perilous world of lies and deceit - peppered with the occasional trace of honour. This is BBC drama at it's best - slowly paced, certainly, but intimately photographed avoiding graphic imagery, contemplative and illustrative of just how wheels turned within wheels; or maybe dolls lived within dolls.