It appears that the refurbishment of the Virgin First Class Lounge which reduced the number of seats is causing overcrowding.

Hence Virgin have reduced how long you can enter in advance of your train to 2 hours before departure (and one hour after arrival) unless you have one of their most expensive Anytime tickets.

Between 3pm and 7pm it is reduced to only one hour before departure.

Don’t plan on getting there early and working before your train.