Bloomer was a name used to refer to three similar classes of 2-2-2 express passenger locomotives designed by James McConnell for the Southern Division of the London and North Western Railway (LNWR).

The nickname was a topical one in the autumn of 1851 when the first engine arrived on the line, because of the current popular excitement aroused by the appearance of women wearing trousers, as advocated by Mrs Amelia Bloomer.

Apart from two of the 6 ft 6 in engines which were scrapped in 1866, all the Bloomers were given nameplates in 1872; the names awarded were of the usual miscellaneous variety customary on the LNWR.

A further twenty examples were built in 1861/2: five by Sharp Stewart & Co., five by Kitson and Company, and ten at the Wolverton railway works of the LNWR.

* Number assigned, but possibly never carried Eleven smaller examples were built with 6 ft 6 in (1.981 m) driving wheels in 1854 for use on secondary fast main-line trains and branch lines of the Southern Division.

These engines were originally intended by McConnell to be a 7 ft-wheel variant of his Patent class, but the design was altered by order of the directors to a smaller version of the successful Bloomers.

Three examples were built by Wolverton Works with 7 ft 6 in (2.286 m) driving wheels together with McConnell’s patented firebox in 1861, which were intended for the fastest expresses.

An accurate full-size, non-working replica was built, by apprentices, for static display outside Milton Keynes station in 1991.