Thanks guys. Yes, there's a lot in the hangar, quite a few of which were outside for a while.
Those outside are actually covered in winter, or at least cockpits and other 'delicate' areas, but, as the museum is open all year round, apart from Christmas day and Boxing day, covering them totally would defeat the whole purpose of the museum.
I certainly wouldn't like to travel the distance from where I live, pay to get in, and then find a load of canvas 'humps' on the tarmac, instead of visible aircraft.
As with most such museums, privately funded, and started by enthusiasts, preservation work is carried out on the aircraft, vehicles, and indeed the buildings, as and when possible, and when funds permit, by a volunteer group, and preventative maintenance is on-going, even if a full (and very expensive) re-paint of aircraft is not immediately possible. (the 'Gulf War' Buccaneer had just been re-painted during our previous visit, for example.)
There are plans to erect another 'T2' hangar, with the area to the side and rear of the existing hangar earmarked, and, of course, the previously mentioned 'Andi det' days are held regularly throughout the year, preparation and servicing for which was being done during our visit.
It's very easy to visit such a museum, and not realise just how much preparation, re-claiming, re-building and preservation of the actual site has been done over the years. All of the buildings on the site are original WW2 structures, fully restored and functional, with some, like the tower, for example, kitted out as they were during the war.
When the museum obtained the use of this part of the airfield site, all of these buildings were derelict - they were crumbling and peeling, overgrown with brambles, and with vegetation taking over inside !
Karl and I posted a more in-depth thread on the YAM during our visits two years ago - in torrential rain, and then in blistering sun - which show some of the other museum attractions, but as a reminder, here's just one shot of part of the original, WW2 buildings on site.