Re Mar 2013 Tim Pullens report on how to insulate old homes. He says NO VENTILATION/AIR SPACE is required between granite/lime mortar walls and internal plaster and lathe. From the eaves 1st floor i can see right down to ground level between the 2/3″ air gap and could easily fill it with hygroscopic insulation. However this conflicts with everything i’ve read and learned over the last 6 years about leaving a ventilation air gap. Is there any evidence I could obtain to support this new information please? It’s a 1929 detached granite building with lots of walls to insulate at ground level. Insulating internally and externally is not an option. I would use eco friendly breathable insulation. What would be the long term consequence of no air gap to the internal plasterwork?