If the deceased had given a power of attorney to someone during his/her lifetime, this will automatically cease on the death and not when probate is granted. It is important that the attorney is notified and also the institutions that the attorney was dealing with (eg Bank, Building Society) are informed of the termination of the authority. This can of course be done at the same time as asking for probate valuations.
If the deceased was a sole or joint attorney for someone else then that power of attorney automatically ceases now that the attorney has died. If the deceased was appointed jointly and severally with another person who is still alive, the power of attorney continues in so far as that person is concerned. Nevertheless it is important to give notice to the donor and the other attorney.