1:- Where in any proceedings before any court . . . the custody or upbringing of an infant, or the administration of any property belonging to or held on trust for an infant, or the application of the income thereof, is in question, the court, in deciding that question, shall regard the welfare of the infant as the first and paramount consideration, and shall not take into consideration whether from any other point of view the claim of the father, or any right at common law possessed by the father, in respect of such custody, upbringing, administration or application is superior to that of the mother, or the claim of the mother is superior to that of the father.