Just saying it is aligned means nothing with out a time frame of when it was checked or adjusted and what are the TOE and CAMBER of both the front wheels were finally set at, AND in what shape are the tie rods and upper/lower ball joints in at your 90,000 miles? You could have a mess for all we know. If they have not been replaced yet, this could be another large deviation in suspension integrity. Factory allowable deviation is way too broad and almost every "common" alignment even new can have a large deviation swing as many, but not all, follow wide factory deviation too. Some alignment guys will give you a fairly accurate toe and will not adjust camber as long as it is in the wide swing of factory allowable deviation. High-performance alignments will hit exactly what you want as long as it is in the car adjustment spectrum, and of course cost more. Some shops say they did an alignment and actually did no adjustments and the car/truck could be a good way out of an accurate high quality alignment you should be at if you are hunting for why you are having tire wear. Those tires are not the best choice for a long wearing tire for that truck, as it heavy and I bet puts high load on those tire even in common driving. Thin long syped soft tire against a larger stiffer block lug tire the Defender is.
While other posters suggestions may help, but it is a crap shoot that will need a lot of time and more tire wear to test, and then it subjective as to your memory 2 months later. Knowing your exact alignment specs can help pin it down way way faster. The first place I would look is camber on that front tire. Might that be on the side you may be going on the load side of a exit ramps that you might have a large # you drive on daily to work??? Just throwing that out as a possibility.
. It's a much lighter car though. No idea if that's a contributing factor, but worth noting.