I think adfly has it spot on.
AFAIK SOU is currently an 8 x Q400 Base for Flybe, with one EMB appearing a few days a week to operate Sun routes (which stop again after Easter until June). A few years ago I think there were 6 or 7 x Q400 and 3 x 195's based (the 195's did a lot more than the Sun routes at that time).
The Summer is looking good, but I'd be concerned about over-capacity now on some routes, AMS being the one that springs to mind with KLM starting and Flybe upping frequency.