Hatton's posted these more or less as soon as Paddy made the announcement.
As @BosKonay says, we'll hear it here when it's true!
(Just like some two-tone green Dublin buses, ahem...)
And as @Ironroad says, best thing to do is add them to your Hatton's wishlist.
Hatton's Murphy Models list:
https://www.hattons.co.uk/stocklist/1000501/0/murphy_models/mfrnest
I think that it was the Cravens which were being considered, based on sufficient interest, and these are not listed on the Hatton's website.
Also to note, quite strangely, is that the new run of 141's and 181's is not listed on Hatton's, even though Paddy had samples at the Raheney show.