It then occurred to me that Mr Patten really had been witty and amusing, and that the BBC man was using the wrong word about him. For there's something vaguely pompous about humorous. People who say "humorous" when all they mean is "funny" tend to be the sort who themselves lack a sense of humour. The only appropriate use of the word, it seems to me, is for describing something that is not funny. "Very humorous, I'm sure" one might say, in a facetious way, about someone who has been over-facetious themselves.
Humorous is first cousin to jocular, another iffy word. Tom McArthur's Oxford Companion to the English Language says that The Importance of Being Earnest is "humorous in its basic situations" and "witty in the comments made by the characters". I don't think Oscar would have been too happy with that.
But this is tricky terrain. Everyone knows that one man's witticism is another man's "feeble attempt at humour". The really intriguing thing about humorous is how it has managed to achieve an effortless 180-degree turn. To Shakespeare and his contemporaries it usually meant "grumpy". When Jaques, the philosophising courtier in As You Like It, says he is often "wrapped in a most humorous sadness" you can take it he's not joking.
One can see how it happened. Humor was the Latin for moisture, and according to medieval doctors a humour was one of four kinds of bodily fluid (blood, phlegm, choler and black melancholy) that determined your disposition, or mood, which might be happy or it might not. Humorous people were people whose juices were working overtime, and at first it was assumed that this made them what we call moody, then that it made them whimsical, quirky and fantastical, and so comic. Thus a "humorous" person changed from being someone in a bad mood to someone in a good one.
The change was gradual and the meanings depended on the contexts, but I don't think we have quite lost, even now, the old feeling that to be humorous is to be ever so slightly tiresome. Its noun has avoided this problem, and can be as neutral as you like; one can be in a good humour one moment, a bad one the next. And no one objects to a humorous smile. But spare me, please, from too many humorous jokes.
PS: I have since seen a couple of reports, and I can see that the BBC was indeed wrong about Mr Patten. The word should have been chirpy.