They were built by Dubs & Co. in 1870, and were very similar to the 690 Class.

They were double-framed engines with a back tank behind the cab under the bunker.

They were all originally fitted with condensing apparatus for working the Metropolitan lines.

780–783 were transferred to the duplicate list as Nos 780A–783A.

1212 was withdrawn in 1921, but the remaining 19 were inherited by the London, Midland and Scottish Railway at the Grouping in 1923.