On 30/04/2021 10:42, Mike Halmarack wrote:
On Fri, 30 Apr 2021 10:33:42 +0100, Algernon Goss-Custard
wrote:

Mike Halmarack posted
The main door of my flat has 2 yale type locks and a Mortice lock.
The mortice lock key is the only one I ever received.
It's only when the plumber came to do some work that I realised the
possible problem of having two potentially self locking devices on the
door with no key to open them from the outside.

How do you mean, "possible" problem? How do you get in at the moment
without having keys to the Yale latches?

By leaving them permenantly held back.
Something that the plumber and his mate weren't sure about when they
left at the end of the day.

How do I overcome this? Will a Locksmith be able to provide the means
of making these locks fully functional, with minimum cost and work
involved, or will a complete replacement be necessary?

If they are ordinary Yale locks you can buy replacements at B& Q for a
few quid. They are easy to fit yourself.

They're not that ordinary. One is a "KEN" and the other a "Century".
The Ken has a bezel the other not. I don't know how standard or
interchangeable they are.

For now I would remove the inner locking part. These typically
sit surface-mounted in the inside of the door and usually held
in place by a couple of screws into the edge of the door and one
more at the far end.
This should leave the actual lock barrel in the door with a
flat 'tail' poking into the inside of the door, that engages with
the lock slider.
I suspect the lock barrels are standard and easily replaced with
new ones from any decent hardware store.

Post a photo for us to confirm what you have.