Wow, that was quick!
Thank you, I thought the protruding beams might be the case - we have similar construction in Malta using wooden beams to support limestone blocks for roofing, and although they are often flush with the wall in some instances you can get the odd protrusion.
Etranger - that sounds very interesting. Could make for an interesting addition to a model; and again we have that here in Malta with limestone construction too.
Thanks guys.