The 11th Doctor’s velvet waistcoat (usually) had three welt pockets: two lower pockets and an upper left pocket.
As best I could tell, there was never an upper right pocket.
All three pockets slanted upward away from center.
The same trim used on the waistcoat’s front (and “Snowmen” frock coat) also decorated the side and upper edges of the pocket welts.
The precise positioning of the pocket welts may have slightly varied, but the centermost lower corners of the lower pocket welts seem to have been level with the center of the second-lowest button (and buttonhole).
(The dotted lines in the examples above may look crooked, but they were squared out from the front edge.)
The upper left pocket welt appeared to be angled parallel to the lower one, although the upper welt was smaller than the lower one.
The upper left pocket appears to have been positioned so its centermost upper corner was level with the third-highest/fourth-lowest button.
Sometimes, though, that upper pocket welt appeared to be slightly lower …
We can probably just chalk this up to human error, though – either on my part, or that of the original costumers.
(Again, the dotted lines in the examples above were squared out from the front edge.)
At least one of the velvet waistcoats, though, had an upper left pocket welt that appeared to be positioned quite a bit lower than the others.
Two final peculiarities regarding the velvet waistcoat’s pockets:
First, one waistcoat appeared to not even have the upper left pocket!
Granted, both the scene and the velvet fabric were quite dark and the details are difficult to make out, but you can see the light hitting the decorative trim on the lower pocket welt … but not an upper one:
And finally, the buttons were attached to the right side of the waistcoat, with the buttonholes on the left – as is traditional for men’s garments.
However, there was also this flipped shot from “The Time of the Doctor,” in which the opposite was actually the case – and the upper left pocket was actually on the upper right!
Again, Doctor Who has a built-in defense against continuity errors when “timey wimey” stuff is happening; in both cases, the Doctor was close proximity to a literal crack in the universe for hundreds of years … so who knows?