Lord Bracknell
On fire
Rarely ... very rarely ... is a HUGE picture welcome on NSC.Sorry! Can't work out how to re-size.
This may well be one of those occasions.
Seriously though ... I remember the engineers telling the Falmer For All team a while back that the whole point about the design of the arch is that it will move. Its precise configuration at this stage in the construction process is determined by the position of the temporary supporting towers and the pull of the crane. These are adjustable. Once the supporting towers are removed and the arch itself starts to do its job - holding up the roof - the whole thing shifts (a lot) and a new set of stresses start to apply. But everything is designed to pop into place throughout the process of construction.
The final pop is the one that matters. Engineering is a very mysterious art. It always looks hairy to people who aren't practitioners.