With their names evocative of the industry for which they were intended, Gaslight and Whitemantle were a pair of essentially identical sisterships completed in 1920. Built by Wood, Skinner at Newcastle for the Gas Light & Coke Company (Stephenson, Clarke & Co. of London, Managers), Gaslight was registered at 1,696 tons gross (997 net) and Whitemantle, slightly lighter, at 1,692 tons gross (993 net). Each measured 260½ feet in length with a 37½ foot beam and both were fitted with triple-expansion 3-cylinder engines manufactured by the North East Marine Engine Co. at Wallsend. Curiously, Lloyd's Registers note that Whitemantle's engines were markedly more powerful than her sister's and also state, somewhat ironically for a pair of colliers, that Gaslight was "fitted for oil fuel."

Gaslight remained in service until the late 1950s, by which time her owners had been transformed, thanks to nationalisation, into the North Thames Gas Board; Whitemantle was less fortunate however and fell prey to a German mine west of Withernsea, Humberside, on 22nd October 1939. Bound for London from the Tyne with a full cargo of coal, she sank rapidly after striking a magnetic mine with the loss of 14 lives.