Thanks for such a prompt reply. I thought it might be something like that.
Meanwhile I've just found probate for my grandfather the previous year, 1965 to the same 2 people, my late uncle and the family solicitor.
My Great grandfathers effects were £598, my grandfathers £2210, not a great deal but obviously worth more then than today.
My aunt & uncle dealt with the estates of several close members of our small family over the years. As he was an Insurance manager I guess he was familiar with finances.