Land registry

My father partner passed away 5 years ago. She’s still on the land registry but her wil states everything goes to my father. He has now since passed away would this be a problem with her being left in it & would it be a problem with the sale of the house. & also her children are questioning there attachment to the house with her name being on the registry. Kind regards Darren

Darren - when a joint owner dies the legal ownership, which we register, passes to the surviving joint owner to deal with as appropriate. Her death is factual and can be proven at any time by submitting a certified copy of her death certificate. 
The death of your Father now means the property forms part of his estate and probate is required. Probate will provide his executor with the legal authority to deal with his estate inc the property and sell it if that's what's to happen
A buyer can usually rely on the registered information plus certified copies of both her death certificate and his probate to complete