It's pretty unusual to bring the touring lead when announcing a new major production. Brits love it when American stars come over (despite the fact that she's not really known in the UK). She also won the Tony for this, so it makes sense for them to bring her over and hope for her to win an Olivier. Plus, didn't Laura sort of allude to the fact that she enjoys working in the US more than the UK?
Bring Back La Paige! It was so much fun watching her fight for dear life to get out of that gigantic frock. She looked like a poor little person clinging onto a rock while the waves are crashing around them.
And Kelli O'Hara was clearly a fan too because she stole Elaine's accent for the show.