4 Correct answers (and here are links to my sources). No reports of crowded scenes at Euston though (quite the reverse) and one still to be identified - a station that I know many members have passed through.
1. Kensington Olympia otherwise known as Addison Road. - TonyNhttps://www.mylondon.news/lifestyle/travel/kensington-olympia-secret-underground-station-26648671Originally opened as Kensington station in 1844, the station was so unpopular it closed in December that same year. It reopened with new services, including the Metropolitan line, in 1862, and in 1868 it was renamed Kensington Addison Road.
2. Holland Park - PrestburyRoadhttps://en.wikipedia.org/wiki/Holland_Park_tube_stationThe original building was typical of those designed by Harry Bell Measures for the stations of the Central London Railway that opened on 30 July 1900. It was given a flat roof in the hope that commercial development would take place on top, as at Queensway station, but so far this has not happened. The building was refurbished in the 1990s.
4. Sugar Loaf - Hafrenhttps://en.wikipedia.org/wiki/Sugar_Loaf_railway_stationThis station is a request stop used mainly by trekkers and cyclists, since it is the nearest stop to the Sugar Loaf vantage point, although it was originally built to serve a number of cottages occupied by railway workers (such as signalmen and track gangers).
6. Moorgate - JayMachttps://www.ltmuseum.co.uk/whats-on/hidden-london/moorgateThe station opened in 1865 as Moorgate Street on the first extension of the Metropolitan line joined in 1900 by the first extension of the Deep Tube. Remarkable re-designs and station upgrades have left behind a maze of disused tunnels, abandoned track and a complete Greathead shield from 1904, the only one of its kind on the London Underground Network.