The British National Party is a right wing, white supremacist party. Rather than seeing Immigration as an obstacle to a "green" Britian, they see the "green" rationale as a means of achieving the marginalization of non-white immigrants.

Wikipedia:
According to its constitution, the BNP "stands for the preservation of the national and ethnic character of the British people and is wholly opposed to any form of racial integration between British and non-European peoples", and is "committed to stemming and reversing the tide of non-white immigration and to restoring, by legal changes, negotiation and consent the overwhelmingly white makeup of the British population that existed in Britain prior to 1948". To achieve this aim, the BNP advocates the use of "firm but voluntary incentives" to remove ethnic minorities from the UK.[3] Membership of the party is restricted to "Indigenous Caucasians." [2]