Commonwealth citizens resident in the UK are generally allowed to vote in UK elections, even if they aren't British citizens. There's been some controversy over this provision. For example, Migration Watch UK calls for an end to the practice, saying that there's around 1 million Commonwealth citizens eligible to vote in the UK, and some recent UK elections were decided by less than a million votes. Thus "Commonwealth citizens voting can potentially have a significant impact on UK elections".
But is there any actual impact on UK elections? For example, have election candidates appealed to non-British voters, particularly in areas where Commonwealth citizens are highly concentrated?