Whenever people feel the status-quo is failing them, or disintegrating, they move to the political extremes, for obvious reasons. Labour has moved to the centre - to defend the status-quo - just as lots of voters are moving away from it. Which way voters move though is not necessarily rational - most people are not well informed, nor are they particularly interested in politics - at least as politics is represented in the media. They know they want things to change, but don't know who to believe will make the right changes.
Left/green and right are opposed only in terms of their ideas and values - voters move easily between them. It's well recognised in France that a large group of RN (extreme right) voters are former communists. They were never really communists, nor are they now fascists - but the Communist Party once seemed to offer a credible route out of their oppression, now RN seems a more immediate prospect.
Maybe, like Americans, they have to actually see the right fail before coming back to the left.
