“(1) Where an immigration decision is made in respect of a person he may appeal to the Tribunal. (2) In this Part "immigration decision" means - …… (d) refusal to vary a person's leave to enter or remain in the United Kingdom if the result of the refusal is that the person has no leave to enter or remain.”
“[35] The key to the matter is an understanding of how s.3C operates. I have set the section out at para 10 above. The section applies, by subs.(1), where an application for variation of an existing leave is made before that leave expires (and provided that there has been no decision on that application before the leave expires). In that event there is, by subs.(2), a statutory extension of the original leave until (a) the application is decided or withdrawn, or (b), if the application has been decided and there is a right of appeal against that decision, the time for appealing has expired, or (c), if an appeal has been brought, that appeal is pending: I paraphrase the statutory language, but that seems to me to be the effect of it. During the period of the statutory extension of the original leave, by subs.(4) no further application for variation of that leave can be made. Thus, there can be only one application for variation of the original leave, and there can be only one decision (and, where applicable, one appeal). The possibility of a series of further applications leading to an indefinite extension of the original leave is excluded. However, by subs.(5) it is possible to vary the one permitted application. If it is varied, any decision (and any further appeal) will relate to the application as varied. But once a decision has been made, no variation to the application is possible since there is nothing left to vary.”
“For the purpose ofsection 3C of the Immigration Act 1971 an application for variation of leave is decided— (a) when notice of the decision has been given in accordance with regulations made undersection 105 of the Nationality, Immigration and Asylum Act 2002 ; or where no such notice is required, (b) when notice of the decision has been given in accordance withsection 4(1) of the Immigration Act 1971 .”
“(1) The Secretary of State may make regulations requiring a person to be given written notice where an immigration decision is taken in respect of him.”