A new-born infant who, after commencement, is found abandoned in the United Kingdom [F4, or on or after the appointed day is found abandoned in a qualifying territory,] shall, unless the contrary is shown, be deemed for the purposes of subsection (1)— (a)to have been born in the United Kingdom after commencement [F5or in that territory on or after the appointed day]; and (b)to have been born to a parent who at the time of the birth was a British citizen or settled in the United Kingdom [F6or that territory]