John Le Carre's son, Nick Harkaway, joins Simon and Matt for a chat about his new Circus novel.

They discuss the challenges (and joys) of taking on the mantel of such an iconic character (George Smiley) and writing in his father's footsteps, as well as the research it takes to get the technology of the time right.

As well as lots of espionage stories, they chat about John Le Carre, his voice, his style - and why Nick decided to write this novel in the first place.

The book is Karla's Choice - and you can read more about it here:

It is spring in 1963 and George Smiley has left the Circus. With the wreckage of the West's spy war with the Soviets strewn across Europe, he has eyes only on a more peaceful life. And indeed, with his marriage more secure than ever, there is a rumour in Whitehall – unconfirmed and a little scandalous – that George Smiley might almost be happy.But Control has other plans. A Russian agent has defected in the most unusual of circumstances, and the man he was sent to kill in London is nowhere to be found. Smiley reluctantly agrees to one last simple task: interview Susanna, a Hungarian émigré and employee of the missing man, and sniff out a lead. But in his absence the shadows of Moscow have lengthened. Smiley will soon find himself entangled in a perilous mystery that will define the battles to come, and strike at the heart of his greatest enemy…