Manchester and Liverpool still have plenty of capacity. The focus should be on using available capacity to the most efficient way possible before spending millions on a new airport in the nearby vicinity. (And that's not a dig at ATC or ground handling at either airport who do a great job under pressure as it is)!
And regarding re-routing flights...!
"Hi is that Ryanair? Hi I'm the Manchester Airport General Manager, would you mind re-routing your flights around the north a bit to free up some space to land aircraft at Manchester?"
Sorry can't see any airline at all agreeing to re-route flights on a longer route wasting hundreds of thousands of £££'s each year to allow an extra few aircraft per hour land at their destination.
Then again, I saw mommy kissing Santa last year, who knows what will happen next
Have a great christmas all, do take my post with a pinch of salt or two.
RR