Was it a technical issue with the plane, or a situation such as fog? MXP isn't as affected by it as LIN, for instance.
From an engineering point of view, both airports are now outsourced. I think in both cases the line maintenance is provided by Alitalia; their engineers are usually quite good. MXP also has the advantage of a fully-equipped hangar, owned and used by Lufthansa Technik, where they do Line and service checks on EasyJet and various carriers; I don't know, however, if BA has any agreement there with LHT besides the usual spares sharing system.