§ Dr. Julian Lewis
To ask the Secretary of State for the Home Department what effect the marriage of a prisoner to a foreign national has on the rights of(a) the marriage partner and (b) existing children to (i) remain in the United Kingdom, (ii) hold a British passport and (iii) obtain British citizenship. 
§ Beverley Hughes
If the prisoner is not, himself, a British citizen or a person settled in the UK, then his status would not confer any entitlement on his spouse and children to remain in the UK. Providing that adequate funds were available, his spouse and children could seek leave to enter the UK for short periods to visit him in prison.
If the prisoner is a British citizen or person settled here, a foreign national marrying him would be able to apply for leave to remain here on the basis of the marriage. The application would be considered on its merits, taking into account the following factors:the length of the sentence;whether the marriage is subsisting and the sponsor (that is the prisoner) supports the application and intends to resume co-habitation on release;865Wwhether the spouse is able to maintain and accommodate herself and any dependants without recourse to public funds, given that the sponsor is in prison.
Any dependent children (under 18) could apply for leave to enter or remain in line with the conditions of the spouse.
Marriage to a British citizen does not confer automatic British citizenship on a foreign national. The requirements for naturalisation must still be met, although they are less demanding than for naturalisation of someone not married to a British citizen.
A legitimate child born overseas to a British citizen father and non-British citizen mother may be a British citizen from birth, whilst an illegitimate birth overseas to such parents would usually mean that the child was not a British citizen. However, if the parents of an illegitimate child subsequently marry, and the law of the country in which the father is domiciled legitimates a child of the relationship upon the parents' marriage, the child will be treated as having been born legitimate. The child would then be regarded as a British citizen from birth and would be entitled to enter and remain freely in this country.
A person would not be entitled to hold a British passport without first obtaining British nationality.