I've recently changed a Euro cylinder in a back door to one with a thumb turn on the inside so that the occupants can get out more easily in the event of fire and this set me wondering about some mortise locks I fitted a while ago to a wooden door.
The mortise locks tend to get locked from the inside at night and the key left in so that they can be opened quickly but the downside of this is that anyone trying to get in from outside can't as the key's in the way.
I'd like to put a thumbturn on the inside - is this possible with standard mortise locks or would I have to replace them with ones that can take a Euro cylinder?