Speaking roughly, there are four types of television programme: shows that teach you something, shows that entertain, shows where you switch your brain off or have on in the background while you're working to fill the yawning silence that envelopes your soul, and shows that genuinely change your life.

For me, The West Wing is probably first among an illustrious list of television I have genuinely found to have been life changing. And within that universe, one character similarly stands out.

I may want to be Jed Bartlet, I may want to marry CJ Cregg and Sam Seaborn may have helped me get over my irrational dislike of Rob Lowe, but Leo McGarry is the character who invariably gives me most pause for thought.

On the face of it, he's not the kind of character I naturally gravitate towards in other shows: namely bombastic, wisecracking derring-doers who are all much better with women than I am like Alan Shore, Hawkeye Pierce or the Tenth Doctor. Leo is gruff and was "born aged 55". But he's much more than that.

He's not just a high-ranking mandarin, he's the President's most important counsellor and the mastermind behind two election victories. He's not just a middle-aged politician, he's a sage with a staff who have intense loyalty toward him. In short, everyone should have a Leo.

It's the level of surprise that makes Leo such a great character. In spite of being the President's tough guy, an ex-military man and a man to be crossed with the same level of trepidation as a bear on a month-long salmon and honey fast, invariably it is Leo who is responsible for The West Wing's most touching, inspiring and motivating moments.

Sadly, the man who played him, John Spencer, died before the show finished in 2005. In fact, this Friday is the anniversary of his death. And every year since I started watching The West Wing I (along with a couple of friends who know what I'm on about) have celebrated that day as a kind of personal tribute. That may seem like a strange thing to do but I figure in a world that lets a bull loose once a year on cobbled Iberian streets and celebrates National Sausage Week, a day commemorating one of TV's great characters and the brilliant, humble actor who brought him to life.

Coming up to the end of the year, invariably our minds turn to where we've been, and what we'd like to be, and the people we take along with us on those journeys. John Spencer died terribly young at 58, but as long as I live, he and Leo travel with me.

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