Another thing: Johnson's strategy to hold an election *before* Brexit is risky, at best: as long as Brexit hasn't happened then he will be in a dogfight with both the Brexit Party, who may steal vital votes and even seats, and Remain Parties, who might feel energised enough to stop the thing altogether. If, on the other hand, he concedes the timetable to MPs but manages to pass the legislation through anyway, is that not a victory? There is the risk, perhaps, that an amendment for a 2nd referendum would pass, but it's a fairly small risk at the moment -- Parliament has had this option available to it for years and been unable to find the numbers to support it. On the other hand, the reward would be to be seen to have "GOT Brexit Done", and I would have thought this would have been enough to secure a healthy majority, or even a landslide, as the support for the Brexit Party fades away.
I just don't get this strategy. The obsession with a 31/10 exit date may yet backfire on Johnson.