In the end credits throughout season 1, Ben Miller’s character is named as “Sir James Lester” but his title is never used onscreen.

I always confuse this man with Rob Brydon.

So does Rob Brydon, apparently. ;-)

At least, he (or was it Ben?) said in a recent interview that he's taken to carrying a photo of each of them in an attempt to persuade people they've got it wrong when they insist on asking for an autograph from the wrong person.