Generally with this sort of tour they drip feed bits of news so that there is something new to announce every couple of weeks, with a fresh press release, to keep the ticket sales ticking over.
I bet the Fabio and Amy news will get something more official in due course. Fabio and Amy are based in Hull..
Booking Grimsby Auditorium is quite a big deal as it has 1,200 seats - his other venues are around 300-450. If I had to take a wild guess, there will be a guest slot at Grimsby.
Joanne Clifton's tour of Thoroughly Modern Mille finishes on June 24th. Gio's tour (second phase) starts on June 27th. So.... I wonder if Joanne might dance at Grimsby?
Edit: And Gio has retweeted the news about Amy and Fabio... so definitely definite then.