b) Vila uses body language to appear shorter (slumps, looks down, looks

unthreatening &c.

I think Vila has developed skills at Not Being Noticed that serve him both as a pickpocket, and as a non-combatant in jails. Look Small and Unthreatening, and people don't tend to bother you as much. Also, Michael Keating in 1991 looked quite buff in a T-shirt so I think Vila may have better mucles (all the better for second-story work and Running Away) than his outfits revealled.