Thameslink's Twitter team remind people many times a day that the rear first class on
all their services is declassified. In addition to this I have seen the digital screens on Luton-Rainham services say that this section is declassified. So I believe it's likely the member of staff was wrong.
The picture is quite confusing regarding the forward 1st class section. Thameslink have sent two contradictory tweets within an hour of each other today.
Regarding the Luton-Rainham service, they
said:
To me this implies it is declassified all the way from Luton to Rainham, including the core.
Then they later Tweeted in a separate conversation:
To me this implies that the forward first class in in operation Luton - St Pancras, but not the core.
No idea what's going on!