Parliamentary parties in the British House of Commons tend to experience high levels of voting unity with individual MPs only occasionally dissenting from party policy. Although constituency influence has been used extensively to predict legislative behaviour in candidate-centred electoral environments, it is argued here that constituency preferences can, under certain circumstances, shape parliamentary behaviour in a strong-party, weak personal-vote, electoral environment such as the United Kingdom. To empirically test this argument, the interest representation of British Muslims in the British House of Commons and specifically the voting record of MPs on proposed domestic anti-terrorism legislation seen to target British Muslims is investigated. The data shows that Labour MPs with certain constituency characteristics (relatively large Muslim, ethnic minority and migrant populations) were more likely to vote against the leadership position on anti-terrorism proposals perceived to target certain minorities.