John F. McIntosh became an apprentice with the Scottish North Eastern Railway, at the Arbroath workshops, at the age of 14.

By this time he was employed by the Caledonian Railway (CR) which had taken over the SNER in 1866.

Several appointments followed – Locomotive Foreman at Aberdeen, Carstairs and Polmadie (Glasgow); Chief Inspector; Locomotive Running Superintendent and deputy to John Lambie.

Lambie died suddenly on 1 February 1895 and McIntosh replaced him as Chief Mechanical Engineer.

[3] Other designs include: Two McIntosh locomotives are preserved: He obtained patents for a spark arrestor and a gauge glass protector.