Indeed and as the GN twitter team confirmed earlier today, the only declassified 1st Class on their services is on the Class 700 fleet with the rear 1st Class in the direction of travel being declassified.
Class 365s do
NOT have any declassified 1st Class on board in either direction see following tweet:
"Hi Alex - First Class is only declassified on the Class 700s. Class 365's wont have declassified 1st class I'm afraid." ^Sam
https://twitter.com/GNRailUK/status/1054318826421186560
They confirm that the rear 1st Class on the Class 700 IS still declassified in the direction of travel see following tweet:
"Hello Alex, first class is only declassified at the rear on the new class 700 trains. On these trains there is only front and rear first class." ^Kim
https://twitter.com/GNRailUK/status/1054314859913973761
IF a non Class 700 does turn up then regardless of what the information systems say, it
DOESN'T have any declassified 1st class at all so if a Class 365 turned up for example then you would be charged a PF if you sat in 1st Class with a Standard Class ticket
UNLESS it is stated otherwise that it is declassified for example due to disruption see following tweet:
"First class is only declassified at the rear on the class 700 units. Unless stated otherwise due to disruption etc." ^Kim
https://twitter.com/GNRailUK/status/1054316191681036289
I hope that settles any discussion that there might be?