A film I liked which other people may not have seen is Siete días de enero. it's a film about the shooting of five spanish communist party members in 1977. It's good if you're interested in spanish history, especially la transición. You can watch it on daily motion (without english subtitles unfourtunately).
'The Crying Game' (1992) is not leftist, but it's about the IRA and it's really good.
More openly marxist is 'Sorry to bother you' which came out last year and is really worth watching if you haven't already.
Two films which involve lots of members of the british aristocracy being killed (which of course I don't support):
If… (1968) which is on youtube in good quality.
Kind Hearts and Coronets (1949)