After my grandmother died my aunt stayed on in the family home until she died herself last year. We assumed that the property would be divided among the rest of the family, but the house has gone to a single grandchild, which has caused a family rift. We don’t believe this was my grandmother’s intention, but her will cannot be found.
It’s possible your grandmother signed over the house to your aunt while she was alive, in which case it will now have passed to your cousin either through your aunt’s will or under the intestacy rules. You can check on the property’s ownership details at the Land Registry, and check whether your grandmother made a will online at www.gov.uk/search-will-probate.