I have received a communication from the Department for Transport in response to a query about the lack of available electric trains for Liverpool-Manchester and Liverpool-Wigan services in 2014.
They say that "... it was assumed that Class 319s would be cascaded from
Thameslink to operate the service. Whilst that still may be the case,
it has emerged that vehicles from other sources could be available too."
They don't go on to explain what those sources are.