WHEN I need an escapist diversion, I often read one or all of the books in John le Carre’s Karla trilogy. Swedish director Tomas Alfredson’s deft guiding of the first book through this change of medium works well.

Whether you do or don’t see it without having read the book, doing both will reward you.

Scriptwriters Bridget O’Connor and Peter Straughan, cutting some corners and adding invented touches without diminishing its impact, have made variations to what began on the printed page as a tense, densely-packed, complex secret service thriller. Le Carre obviously was comfortable with how director and writers proposed to deal with the book – he’s listed as a co-producer and appears briefly in a sequence not in the book.

As George Smiley, recalled from semi-retirement to track down a suspected mole, Gary Oldman did not closely fit my mind’s image of Smiley’s physical presence. No matter. That one-time wild lad of acting plays him convincingly. None of the supporting cast matches my visions of their characters, but they know what they’re there to do and do it convincingly.

I have only two complaints. Smiley’s acolyte Peter Guillam is not gay. And to Connie Sachs, a natural for the late Margaret Rutherford, Kathy Burke brings too much polish.

For those who haven’t read the story so don’t yet know who the mole is, finding out is definitely worth the wait. The film reveals him in a similarly low key, only different.

At Dendy and Greater Union