"We do not therefore think that the questions which the court has to answer in assessing a claim under the Act necessarily always divides neatly into two. Adequacy of the provision that has been made is not to be decided in a vacuum, or by looking simply to the question of whether the applicant has enough upon which to survive or live comfortably. Adequacy or otherwise will depend upon all of the relevant circumstances, which include any promise which the testator made to the applicant, the circumstances in which it was made, and, as here, changes in arrangements between the parties after it was made. These matters however will never be conclusive. The age, capacity, means, and competing claims, of all the potential beneficiaries must be taken into account and weighed with all of the other relevant factors." [8]