In this instance i imagine that it was a case of get down as soon as possible. As it seems they just started to fly over the river severn when they dedected the issue i imagine it was either Cardiff or Bristol.
Runway 30 was active at CWL therefore it may have looked a better option and longer runway could have also played a part.
But the way in which it was handled and the comments not only from the airline but by the passengers themselves was a testiment to a job well done.
This will fill airlines with confidence that they can rely on non base stations such as CWL in the future for Diversions.