It was okay when seen on release but the characters haven't aged too well and are now (in 2022) two a penny. Although it is well produced some of the violence is over the top.
It may have an intelligent screenplay but the casting of Wood was bizarre & a distraction. When he appeared I went into Enid Blyton mode. Tragically Anna Massey is limited to a cameo but there is John Hurt & the dependable Jim Carter to get you through.