A student is a person who is enrolled, for the principal purpose of following a course of study (including vocational training), at a public or private establishment which is financed from public funds or otherwise recognised by the Secretary of State as an establishment which has been accredited for the purpose of providing such courses or training within the law or administrative procedure of the part of the UK in which the establishment is located, who has comprehensive sickness insurance in the UK, and who assures the Secretary of State, by means of a declaration, or by such equivalent means as the person may choose, that he has sufficient resources not to become a burden on the social assistance system of the UK during his period of residence.