Advice regarding removing time lock.

[davenutt]

I am currently renovating door locks on a listed building that was formerly a Post Office (now in private hands) there is a wall safe with a time lock. The safe is open and we have the keys, the lock and mechanism works fine.
The client has asked us if we can remove the time lock,I have explained that as long as it is not set then everything is fine,however he insists he would like it removed.
The unit is made by Thomas Fox of London.
Is the removal as simple as- back pan off and simply remove the unit. Any advice,pitfalls,things to look out for would be much appreciated.
Have attached a couple of pics,sorry about the quality.