any reason as to why Belfast was given the newest aircraft in the fleet?
I thought it would have been placed at a bigger base
I initially wondered the same BHD2BFS.
Perhaps it is to maximise the fuel savings across the A321 fleet? Outside of GLA (which seems to be a 757 base), BFS probably has the longest sectors from the Uk so the savings will be greater than operating the same route from eg. MAN. I think the new sharklets alone create between 3-5% increase in fuel efficiency and the newer versions of the CFM engines are probably even more efficient than those currently hanging on the rest of the older A321's in the fleet (TCDA, is maybe an exception to that).
Just my opinion though, could be totally wrong!