Hi Sim,

Yes ! - I have not seen the TV programme but a cathedral roof just sits there - no bolts required.

Depending on the roof configuration it will usually have an inner and outer wall plate with some stone infil between the two wall plates.

A book that you could check out if you require further details is "The Open Timber Roofs of the Middle Ages" by Raphael and J. Arthue Brandon.

Regards

Ken Hume