Ten of the engines were new builds supplied by the North British Locomotive Company (NBL) or constructed at the NCC's York Road works.

The rebuilt locomotives were coupled to the original BNCR-type six-wheeled tenders which could carry 6 tons of coal and 2,690 imperial gallons (12,200 L; 3,230 US gal) of water.

They also worked the Larne Harbour boat trains, being allowed 30 minutes for the 24⅓ miles, again over a route with a significant proportion of single track.

Having hauled eight bogie coaches from Antrim to the summit of the NCC main line, a stop would be made at Ballyclare Junction to attach carriages that had arrived from Derry or Cookstown on a previous train before travelling on to Larne Harbour where it was common to see trains of twelve or more bogie coaches arriving.

Originally fitted with Fowler pattern chimneys that had capuchons, some the class, such as No.76, later received a Stanier type and it was said by their crews that they never steamed as well after this alteration.

The initials "NCC" in shaded serif gold capital letters were placed centrally on the tender sides.

Number plates were brass with raised digits and edge; they were carried on the lower cab sides with another placed centrally on the back of the tender tank.

However, No.81 received a coat of maroon paint in 1941 when it was overhauled at the Great Northern Railway of Ireland works at Dundalk in County Louth.

Following transfer of ownership to the UTA, locomotive No.80 Dunseverick Castle was turned out in an experimental olive green livery in late 1948.

No.74 Dunluce Castle was restored into its original LMS (NCC) livery at the UTA's Duncrue Street workshops during late 1962 and in April 1963 was transferred to the Belfast Transport Museum.

This locomotive is the only preserved NCC tender engine and can now be seen in the Ulster Folk and Transport Museum, Cultra, Holywood, County Down.