Boris, once more into the breach. Mr. Johnson — now  a back bencher— is a steward of the cause he made his own: Brexit. The latest reminder that Mr. Johnson is what passes for a conscience on Brexit comes amid news that Prime Minister Sunak is set to strike a deal with Brussels in respect of Northern Ireland. Mr. Johnson’s voice in the wilderness — calling for 10 Downing to keep the pressure on the Continent — is, in our view, the one to heed.