Lagerlout, the aircraft that MON are leasing out are only for the summer season (according to Jethro). Now with the new ski schedule for W12/13 soon approaching (sort of - you know what i mean
) those flights should be operated by MON aircraft - mainly due to the fact the season is quiter and they will have more aircraft to play around with. Not only that but hopefully we will see some new aircraft inducted into the airbus fleet.
I agree exactly with your comment on the aircraft being leased being last minute, but one could also see it from a point of view of that they hold less seats and by using them in a new base they are able to have more of a full aircraft than putting on a a320 or a321 and having half a full plane... see what i mean? So basically MON have probably also took that into consideration EMA wise. Now for BHX they might use them on the Nice route and other new S12 routes that are not fully booked, or they could be using them to fill in the gaps or to swap with a MON a/c that would be running a flight half full - so that it is more economical. If you know what i mean?