Sludge (sewage) disposal vessel. Originally built for Glasgow Corporation and certificated to carry a limited number of passengers, she was sold to Southampton circa 1980 for her final few years. Now preserved in Southampton.
Shieldhall at the Woolston sewage jetty on the River Itchen with the former Vosper Thornycroft Shipyard to her bow, that has all been demolished now and a new residential area has been built on the land.
I live approximately a 10 minute walk to this location where you get a good view of the ports Eastern Docks.
It was a trip out of the city and it was free. These ships were kept in immaculate condition and you'd be hard pressed to tell you were on a sludge boat, even when they discharged tanks.
Edinburgh latterly had a similar vessel which also carried passengers.