The cascading of stock from operator to operator seems to be a constant process at the moment with the continual introduction of new trains releasing older stock enabling it to go elsewhere. The last time I saw 170458 it was standing on Edinburgh Waverley back in 2016, see......
https://www.ontheupfast.com/p/21936chg/25778314204/x334020-10-37-edinburgh-waverley Now, wearing Northern's new livery, it is seen leaving Sheffield working the 11.57 to Hull.