"(4) A person's leave to enter or remain in the United Kingdom shall lapse on his going to a country or territory outside the common travel area (whether or not he lands there) unless within the period for which he had leave he returns to the United Kingdom in circumstances in which he is not required to obtain leave to enter; but, if he does so return, his previous leave (and any limitation on it or conditions attached to it) shall continue to apply"
"(2) … may be examined by an immigration officer for the purpose of establishing -- (a) whether there has been such a change in the circumstances of his case, since that leave was given, that it should be cancelled … "
"13 (2) Subject to paragraph (3) where a person has leave which is in force and which was: a) … b) given by an immigration officer or the Secretary of State for a period exceeding six months, such leave shall not lapse on his going to a country or territory outside the common travel area."
"(5) For the purposes of paragraph 2 and 2A of Schedule 2 to the Act (examination by immigration officers and medical examiners), leave to remain which remains in force under this Article shall be treated, upon the holder's arrival in the United Kingdom, as leave to enter which had been granted to the holder before his arrival."
"(1) There has been such a change in the circumstances of that person's case since the leave was given, that it should be cancelled..."
"26. In our judgment, therefore, the Secretary of State was not creating novel powers of cancelling the limited leave that was outside the purpose of section 3B, rather her predecessor was creating a novel class of non-lapsing leave to remain that would justify admission to the United Kingdom after the trip abroad but needed to temper this new provision by applying the same powers of cancellation to it as if it had been a form of entry clearance or leave to enter. The power to cancel such leave was needed as an ancillary provision to the new class of non-lapsing leave "
"...cumulatively, both factors remove the entire basis on which leave to remain had been granted pending appeal."