Caledonian Sleeper have now opened a new lounge at London Euston-
https://www.sleeper.scot/euston-guest-lounge/?utm_medium=email&utm_campaign=October%202023%20Emailer%20-%20Euston%20Guest%20Lounge&utm_content=October%202023%20Emailer%20-%20Euston%20Guest%20Lounge+CID_8831470a71003a78dd4362a33675cf08&utm_source=Caledonian%20Sleeper%20eMarketing&utm_term=FIND%20OUT%20MORE%20ABOUT%20OUR%20EUSTON%20GUEST%20LOUNGE
Open from 1800 nightly (except Saturday when no sleeper trains run), and in the morning until 1030- only for for Caledonian Double & Club Room Guests
They have always previously used the Avanti First Class Lounge