"Generally, children aged 18 or over must qualify for admission in their own right; but an unmarried and fully dependent son under 21 or an unmarried daughter under 21 who formed part of the family unit overseas may be admitted if the whole family are settled in the United Kingdom or are being admitted for settlement, and adequate support and accommodation is available for them in the United Kingdom."
"A passenger who holds an entry clearance which was duly issued to him and is still current is not to be refused leave to enter, unless the Immigration Officer is satisfied that: (a) false representations were employed or material facts were concealed, whether or not to the holder's knowledge, for the purpose of obtaining the clearance, or (b) a change of circumstances since it was issued has removed the basis of the holder's claim to admission...."
"A person in respect of whom directions may be given under any of paragraphs 8 to 14 above may be detained under the authority of an immigration officer pending the giving of directions and pending his removal in pursuance of any directions given"
"Except as otherwise provided by or under this Act, where a person is not patrial - (a) he shall not enter the United Kingdom unless given leave to do so in accordance with this Act."