Question for landlords

[sodastreamer]

Quick question here.... I'm a landlord and have a tenant checking out soon. First time in this situation (tenant was there long term) and to ensure security between tenancies and also for future tenants, I intend to replace the front door lock. I seem to remember (from having done this in my own home once) that I need proof of ownership for the locksmith. How do I go about that when all utility bills have been in my tenants name and my driving licence has my own address? Do I need photographic ID? I'm really struggling to see how I can prove ownership. I have very old bills with my name and the address as it's a house I lived in before having to relocate for work, but nothing current.

Mortgage statement, or download a copy of the title from the LR for £3. Though I’ve never had to prove ownership when getting my locks changed (which does seem odd when you think about it, but I suppose who can prove they love somewhere if they’ve accidentally lock themselves out or lose their keys?)

You can also change a barrel lock quickly and easily yourself.

@ComtesseDeSpair thanks!
From what I read, if you're locked out then a locksmith can let you in, but needs proof of ownership before they leave, as presumably people can normally lay their hands on something in their house.
I'll look out something to do with the deeds or mortgage

If you have the keys and are in the house it’s not a problem.

I've never had to give proof of ownership to a lock smith.