Access involving lock change and owner's permission

Hello, first time poster here, new to the role as well.

I have a very specific issue - I have an empty property with some history of contact between the previous holder of my post and the owner. In previous discussion, the owner had agreed he would like to sell the property however, he lives abroad and does not have a key to the property and no one holding keys for him.

The last contact seems to have been more than a year ago (from sketchy records), but, assuming this issue was never resolved... Is there a way for the owner to authorise a lock change remotely?

miscellaneous issues

Definitly - I recently had an owner in Australia - they just have to google a local locksmith and pay them - the locksmith won't want to hold the keys for any length of time but if they are selling I assume an agent - or auction house would take them? If not we held them for a short period between lock change and sale. :-)

Thanks so much for the swift reply! Still trying to get to the bottom of where the owner and my predecessor were up to with the lock change situation, it appears a locksmith was engaged at one stage... The plot thickens! XD