My family argue that it is necessary to vote in elections to prevent a more evil leader coming in to power and harassing the Muslims?

Answer

If it is possible for a government favourable to Muslims coming to power by Muslim votes, especially in an evil country such as UK, then it will be permissible and necessary to vote for that party. This becomes a 'necessity' due to the gross deficiency of Imaan and the corrupt state of the Muslim community. If the Muslim community is truly Islamic, then there will be no need for this stratagem. Allah Ta'ala is a Sufficient Protector. But since Muslims have made the kuffaar their leaders, Allah Ta'ala has made them our rulers.