The first two were launched in 1935: Inventor by D. and W. Henderson and Company in Glasgow; and Explorer by Swan, Hunter & Wigham Richardson in Wallsend, County Durham.

However, Lithgows in Port Glasgow built most of the class: Tribesman and Strategist in 1937; Scientist in 1938; Adviser and Barrister in 1939; Dalesman in 1940; and Prospector and Geologist in 1944.

It was augmented by an exhaust turbine, which drove the same propeller shaft via a Föttinger fluid coupling and double reduction gearing.

[4] On 18 December 1940, Adviser left Glasgow and joined Convoy WS 5A, which was outward bound from Liverpool.

[8] At dawn on 25 December, the German cruiser Admiral Hipper attacked the convoy in the Atlantic, 700 nautical miles (1,300 km) west of Finisterre.

At 01:45 hrs on 15 November, the U-boat fired another two torpedoes, both of which hit Adviser, crippling her at position 32°03′S 33°52′E / 32.050°S 33.867°E / -32.050; 33.867, about 200 nautical miles (370 km) southeast of Durban.

In fact Adviser, despite being badly damaged, remained afloat, so her Master, Captain John Thurston Ling, and his crew, re-boarded her latre that morning.

On 7 November that year, in the House of Commons, Sir Richard Acland, Bart, MP for Gravesend, asked James Callaghan, Minister of Transport, whether he would publish the reports about living conditions on the ship that his Department had received in recent weeks.

As that evidence showed, an official of the National Union of Seamen agreed with the Surveyor that the accommodation was reasonable and habitable.

It is not of the standard to be found in new ships and the owners have been asked to put right certain minor defects, and to consider the possibility of making improvements.