The choice is yours.
It depends whether the buyer is going to withdraw because you tell him/her to get lost.
It depends whether you want the argument for the sake of the few hundred pounds cost of the replacement or whether they want the argument.
What you don’t want to do of course is replace this and have the cost and then decide they are not going ahead so my suggestion would be that if you are willing to meet them partway with this, you reduce the price by a couple of hundred pounds to allow them to do it or you agree that you will do it between exchange and completion. You would need to get the electrician to schedule that in.
If it was compliant at the time it was installed then there is no requirement to do anything in retrospect.
You are quite at liberty to tell the buyer that you have no intention of doing anything, that’s the price, and they take it or leave it. Of course, they may leave it.
Reallocating consumer unit may be a relatively straightforward job or it can be quite complicated depending on the way the cables run and how much spare wire there is.
It was passed by building regulations whenever, that’s good enough. If the rules have now changed you don’t have to do anything else.
The choice here is yours and the choice of course is theirs.
I am glad to help.
Hopefully, I have answered your query in a way that is simple and easy to understand.
I would be more than happy to clarify anything else for you. In the meantime, thank you once again for using our services.
I am happy to answer any specific points arising from this.
Please be aware that my answer is based strictly upon the information you have given me.
If you still need any points clarifying, I will be happy to reply because the thread does not close. In fact, it remains open indefinitely.
I am always happy to answer any further questions you have on any new thread in which case, please start your question with, “ For FES only”.
You don’t need to do it on this thread, just a new thread. You have me exclusively on this one.