Scott Mills wrote:

Is he not taking about insulating the back of the tiles? If so that would
prevent the convection heating from the tiles into the loft space, although
by how much I don't know. I would have thought there are better products
about.

If the insulation is to go straight onto the back of the tiles, i.e.
between the rafters, then 50mm board (e.g. Kingspan) would be much
better than aluminised bubble wrap.

--
Grunff