Landlord death and notice

I’m trying to clarify who can serve a section 6a notice when the landlord has died.
I am renting a property as the owner was in long term care. I was dealing with her daughter who held Power of Attorney. However the home owner has now died and her will states 2 other people, not her daughter but both beneficiaries of the house in the will along with the daughter are executors. The daughter is not an executor but it was the daughter who served notice 2 weeks after her mothers death and signed herself as the personal representative of her mother. At this stage as far as I can see she was no longer the personal representative as the P of A ceased on death 2 weeks earlier and the personal representatives are now the executors.
As such is the notice valid or should it have been served by the executors as temporary landlords?
Surely the house belongs to nobody until after probate? Thank you for your help

It may be invalid as the PoA no longer applies. However, I’m not sure you could rely on a court not upholding it if you force them to go to court.