Well the BBFC has given it a 15 rating, the other 'Alien' I think all got 18 ratings. Running time 123m 36s.
So is this the cut the same as the US 'R' version or is it an international cut.
Though the version submitted to the BBFc passed with no cuts.
It's probably the same - the 2004 rerelease of Alien was a 15 as well, and the original movie has subsequently been downgraded to that too.