And now the real thing...

Vapour permeable windtight roof tile underlay (Solitex Plus) fixed firmly to the wall, where 180mm of external wall insulation will eventually cover the join. (And yet another air brick to seal up just beneath.)

Once fixed to the insulation board, it just needs the rest of the underlay over the top now. The bottom strip of underlay and the main sheet that goes over the top will be stuck together with a strip of double sided Pro Clima Duplex for air tightness.

All the way round....