[citation needed] In 1936, the entire Williamson-Buchanan fleet, including TS Queen Mary II, passed into the ownership of the London, Midland and Scottish Railway Company.

Later that same year she joined Williamson-Buchanan Steamers (1936) Ltd.[citation needed] During World War II she provided a mail and passenger service to the Scottish Islands.

[citation needed] In the 1960s, there was a decline in passenger sailings on the Firth of Clyde, but TS Queen Mary II continued in service and was refitted for cruises from Gourock to Inveraray, Brodick and Campbeltown.

From 1969 onwards, TS Queen Mary II was placed on almost all of the cruise rosters, and she sailed regularly to Inveraray, Campbeltown, Ailsa Craig, Bute and to Stranraer.

[citation needed] Whilst TS Queen Mary remained very popular in the charter market, nonetheless she was over 40 years old and it was becoming apparent that some major work would be required to keep her in service.

The decision was taken to retire the vessel from service and on 27 September 1977, TS Queen Mary undertook her final public sailing, before being laid up in the East India Harbour, Greenock.

[4][5] However, by 2011, the venture had fallen through and she remained moored in Tilbury Docks, with an uncertain future[6] TS Queen Mary was auctioned by Capital Marine Services on 24 August 2011,[7] and sold to Ranjan Chowdhury.

[9] In February 2015, TS Queen Mary was served with a prohibition notice by the Maritime and Coastguard Agency, preventing her from leaving the Port of Tilbury until made seaworthy.

[citation needed] Eventually the Port of Tilbury put the vessel up for auction, with Friends of TS Queen Mary's bid which was funded by Jim McColl being accepted, the purchase being finalised in October 2015.

Following a survey by the MCA, TS Queen Mary received a Loadline Exemption Certificate and was able to be towed from Tilbury back home to Scotland.