Neighbour asked for help today. Or rather the sister of that neighbour.
They're French.

Neighbours (husband and wife) are in France. Sister house sitting -
presumably because of the two teenage kids at school here.

The front door has once of those night latches where you can lock the
inside handle - to stop the door being opened by breaking the window etc.

And that is on. Both the keys they have open the door from the outside,
but neither will work in the lock in the handle. Probably copies which are
OK in the often used outer lock, but not on the seldom used inner one.

At the moment, one of the kids goes out via the window and opens the door
from the outside...

I offered to remove the lock and see if I could open it in the workshop.
but thought it prudent to talk to the owner first on the phone. Who didn't
want the lock removed. ;-) Tried to explain my lock is similar, and they
come off and go back easily. But although her English is much better than
my French, difficult to get that across.

Obviously, tried some WD 40 type stuff. No success.

Could have just latched it open, but they don't have a key for the fitted
mortise lock.

--
*Why is a boxing ring square?

Dave Plowman London SW
To e-mail, change noise into sound.