Don't have the Charlton, but I have 2 pairs in the 99 last, it's close to half a size smaller, if you have wider feet, I reckon if just for medium size feet, same size.
The Quintessential Dress Shoe: Black Cap Toe Oxford - Page 14
Styleforum Top Picks
My latest cap toe. Part of the Original Collection of the Trading Post, a Japanese shoe store. These are made exclusively for them by Central Shoes Tokyo.
I love how sleek and finely finished these cap-toes are. Notice also the slight tapering of the distance between the lacing holes.
Fit Pic (Please ignore the Chinos I was wearing)
And here it is compared with my "rounder" AE Park Avenues
Warning: Spoiler! (Click to show)