They were designed by John F. McIntosh for the Caledonian Railway (CR) and introduced in 1911.

They passed to the London, Midland and Scottish Railway (LMS) in 1923 and to British Railways (BR) in 1948.

Their numbers are shown in the table below.

The 498 Class was the prototype for the popular 3 1/2" gauge live steam locomotive design 'Rob Roy' by Martin Evans.

[2] This article relating to steam locomotives operated in Scotland is a stub.