Why, Stu? Because Le Pen is a Gaullist, an old-fashioned French nationalist (not forgetting de Gaulle's Irish grandma) who puts the interests of France before anything else, and for whom the interests of England (which is the truthful way of saying 'Britain') are far below anything that may benefit France.

Macron is French first, but European a close second, and will negotiate with Britain to the advantage of Europe, which may more often be also to the advantage of England, or at least more so than when an ultra-nationalist is negotiating along the hard line.