Labour’s crisis is the latest manifestation of a tension that goes back to the party’s pre-history

Labour is facing an existential crisis. Its leader, supported by a resurgent membership, is locked into conflict with the majority of his MPs. Neither side will back down in a battle for the party’s heart and soul. Parallels with the 1980s, when Labour was consumed in civil war while Margaret Thatcher waged war against the communities of Labour’s heartlands, are painfully obvious. But the roots of the current crisis go much deeper, writes Martin Wright