How much "meat" is acceptable around a mortice lock?

Hello

I have just moved into a house. The original owner was a cabinet maker of some renown, and every bit of work completed was brilliant, if slightly mental.

One of these things is the front door. He made it himself. It's intricately carved and looks lovely, but the stile is only 67mm thick.

Would it be acceptable to put a 64mm mortice lock into this door, or am I going to find it weakens the door significantly? I could fit a new door, but there is nowhere else this one could go and it is lovely.

 

It's something to augment the night latch. Are there decent quality narrow nightlatches, then?

 

Specifically, 5 lever ones? It's what my insurance demands.

 

Exactly. The wording of the policy says the door has to be of solid wood construction, in a good state of repair and to have a 5 lever mortice lock fitted. I don't know much about carpentry, but I am a solicitor.

 

Now, to go back to my question, is there a narrow 5 lever mortice lock?

 

OK. The willenhall it is.
Just for the avoidance of doubt, is a 64mm lock going to weaken a door with a 67mm stile to the extent where it will be compromised? Is there an official tolerance, or is it something to argue?

 

I don't need a kitemarked one. My insurance specifies 5 lever, not bs kitemarked.

But thanks you.