1880 - William Henry Allen resigned from Gwynnes and started his own company in York Street, Lambeth, London.

1893 - Richard Allen, son of William Henry Allen, joined the company in partnership with William Henry and the name was changed to 'W H Allen, Son and Company'. Company moved premises to Bedford, England.

by 1921 - company restructured and changed its name to ‘W H Allen and Sons Ltd’.

1927 - Gwynnes, in Chiswick, went into receivership and were purchased by William Fosters of Lincoln. Fosters moved the entire Gwynnes plant to Lincoln as a separate company called Gwynnes Pumps Ltd manufacturing centrifugal pumps.

1960 - Fosters acquired and company changed name to Allen Gwynne Pumps.

1968 - Allens and Bellis & Morcom, compressor manufacturers in Birmingham merged to form Amalgamated Power Engineering Ltd. (APE). The Allen Gwynne business transferred back to Bedford and the Lincoln site was sold. The new APE group included W H Allen, Allen Gears, Allen Gwynnes Pumps, Bellis and Morcom and their subsidiary Crossley Engines of Manchester.

1977 - APE passed into the hands of Northern Engineering Industries (NEI).

by 1988 - Allen pump interests sold to Weir Pumps. Turbine interests sold to a separate company trading as Allen Steam Turbines. The remaining diesel engine business was taken over by Rolls Royce in 1989.