The Battle of Britain Five Months That Changed History, May—October 1940 by James Holland (z-lib.org).epub

Lord Gort, meanwhile, finally caught up with Blanchard at 11 a.m. on
the 28th. The French Army Group Commander walked into Gort’s
command post at around 11 a.m., the same time as the Belgians were laying
down their arms. He was horrified to learn that the BEF was now
evacuating; no-one in the French High Command had told him, although
there was barely any other conclusion that could have been drawn. Gort and
Pownall now urged him to order the French First Army, at the bottom of the
corridor, to join the BEF in falling back to Dunkirk. Gort was planning to
retreat that night to at least the line Ypres–Poperinghe–Cassel behind the
River Yser, some twenty-five miles from the coast. British troops were
carrying out heroic defences along the southern strongpoints of
Hazebrouck, Cassel and Wormhoudt, but in between there had been
significant penetrations. An urgent and consolidated withdrawal was
essential. ‘Whereat,’ noted Pownall, ‘he went completely off the deep end.’
Such a withdrawal was impossible, Blanchard told them, but Gort pressed
his point. There was not a moment to lose.