[Miss Marple]

I would suggest one other reason. He is a small man and few manufacturers produce clothing scaled down for smaller people. (I am short so I know a LOT about this.) It's not just the matter of making the pants legs shorter. Doing that just makes one look like he is wearing culottes. The tailor must also make the pants narrower, as well as the sleeves. Otherwise the suit simply doesn't fit well.

My guess is a lot of his preference had to do with people who knew how to make clothing for someone of his size.

[livius]

It may be that, too, but when I was in Rome, I was amused to see the clergy - including some of our portlier American specimens - running off to the ecclesiastical clothiers that surround the Vatican to get some fine duds! It's a pretty harmless vanity, certainly; and I'd rather have them dressed in a snappy tailored cassock than flopping around in their tee-shirts, as was the fashion not too long ago. I think one of the reasons the Pope dresses well is to emphasize the dignity of the office.