The Caledonian Railway 300 Class were freight 0-6-0 tender engines introduced in 1918 and designed by William Pickersgill.

[2] This was so that they could use continuous vacuum brakes on compatible rolling stock, primarily passenger trains.

In 1923, they all passed to the London, Midland and Scottish Railway, and were classified 3F, and renumbered 17650–17692, along with gaining additional lamp irons.

On nationalisation in 1948, the twenty-nine survivors passed into British Railways stock, and were renumbered by adding 40000 to their LMS numbers.

The first withdrawal of the class was LMS 17657 (CR 302) in Nov 1934 after a service life of 16 years, 9 months.