Only parties which support pr will give us freedom

Anyone who votes for the (fptp-supporting) left-wing party in a two-party fptp system is not helping and are part of the problem. In doing so you are reinforcing and perpetuating the two-party fptp system which privileges the political class. To improve the system we can only vote for parties which are in favour of extending democracy and making it proportional. Even if this means losing the ability to vote tactically it is still the best approach. It is not good to engage with a system which is unfair... you will only strengthen it and give it legitimacy. Fptp is illegitimate and to vote for either of the two fptp parties (both of which support fptp) is to exacerbate the problem.