According to The Sun political editor, Tom Newton Dunn

"Now it's getting tense. Downing Street sources suggest PM may pull the entire WAB if the program motion falls tonight. Program motion only ever defeated once before, on Lords reform in 2011, and bill pulled then. Would he really, or is this brinkmanship? We'll see at 7.15pm."

Is this another calculated gambit/bluff by Johnson? I reckon it'll be quite maniacal to pull the plug on a deal if the WAB motion itself passes but we'll see what happens.