John McDonnell has privately argued that Labour should campaign to prevent Brexit, opening up a new front in Labour’s civil war on Europe.

The shadow chancellor has held private conversations with shadow cabinet colleagues in recent weeks in which he has argued that Labour’s position should be to revoke article 50 and stop Brexit in its tracks.

McDonnell has been a vocal advocate of Labour backing a second EU referendum. But his private remarks go much further and will put him on a collision course with Jeremy Corbyn’s team, who are still resisting full-blown support for another referendum.

Instead, their focus is on forcing a vote of no confidence in Boris Johnson’s government or passing a law that would require him to seek an extension