(I can see that some C42 pilots might, for instance, wonder why a light aircraft one is £12 whereas a microlight one is £7, and so on, but price lists are ever thus.)
I heard the new owner was a microlight pilot (from the grapevine so might be complete rubbish). Also a microlight is a VERY WIDE category, from the weight shifters to basically a Cessna 152 size plane with all glass cockpit. I have a feeling that airfields should differentiate between these.... Not that I fly them anyway...! A few places I've been to, differentiate by both number of engines, and number of seats, which I find quite nice as an alternative to MTOW.