I had my hallway reskimmed, and am now fitting architrave and skirting. The new skim sits proud of the door casing by up to a quarter of an inch, so simply pinning the architrave to the exposed bit of the casing angles it in towards the door, leaving a gap between skim and architrave on the outside.
I'm simply pinning pieces of folded cardboard over the door casing, to level approx. with the skim, pinning up the architrave through it, and aiming to fill the gap where the cardboard is with caulk, before decorating. I'll have done it before anyone replies, but wondered if anyone had an alternative approach.
Cheers Richard