The reason why LAB appears to do so badly in terms of seats for what appears to be a very large vote share is that its support is far less spread over the country than the Tory vote.
A significant part of the Labour vote is in seats with very big majorities and this means essentially those votes are wasted. The Tory vote is spread much more widely
This is one of the reasons why I think Labour will struggle to jump from the 202 seats of the last election to the 326 seats that will be required for an overall majority next time. I have not got any general elections bets yet but my guess is that the LAB overall majority odds won’t offer good value.
It is even possible for the Tories to lose power even if they win most seats. They’ve got to keep losses down to about 47 at the most taking into account the Sinn Fein policy of getting elected but not taking up their seats,