In both scholarly and non-academic discourse, it has long been and continues to be considered important that a national legislature should reflect or resemble the society which it has been elected to represent, for both symbolic and substantive reasons. Indeed, this is considered to be particularly important for groups which have been politically underrepresented in a descriptive sense as it ensures that their interests in relation to policy are adequately represented. Thus far, there has been a degree of academic attention paid to examining the link between descriptive and substantive representation in relation to individuals from a black, Asian and minority ethnic (BAME) background. However, there has hitherto been less attention afforded to the nature of this relationship in regard to the wider immigrant-origin population of the UK, a demographic which includes both BAME individuals and white people with an immigrant background. To examine substantive representation regarding the immigration-origin population, this thesis uses parliamentary questions for written answer submitted during the 2010-15 Parliament. This procedural device is used by MPs to investigate, monitor and scrutinise the governmentÃÂÃÂ¢ÃÂÃÂÃÂÃÂs record, highlight constituency matters and to obtain information on issues and policies of interest to individual MPs. By using data derived from these parliamentary questions, it was possible to establish whether or not British Members of Parliament (MPs) were more likely to have substantively represented the interests of members of the British public who are likewise of immigrant heritage. Its findings demonstrate that immigrant-origin MPs were no more, and were in some cases less likely to have substantively represented the interests of immigrant-origin individuals than their native British parliamentary colleagues. This suggests that descriptive representation is not essential in ensuring that substantive outcomes beneficial to a particular demographic(s) can be achieved. However, BAME MPs, who almost entirely qualified as being of immigrant-origin by the definition used in this study, exhibited a greater tendency to represent matters of interest to individuals from an immigrant background than white MPs, irrespective of their background.