TOPS Class 98 has been used to cover all steam locomotives used on the mainline in Britain, but also has a particular usage for the three Vale of Rheidol 2_6_2T locomotives that remained in the ownership of British Rail after the end of mainline steam traction in August 1968.

Vale of Rheidol Railway Locomotives

The Vale of Rheidol Railway, which runs from Aberystwyth to Devil's Bridge (Wales), opened in 1902, and was later operated by the Cambrian Railway, Great Western Railway and British Rail before being 'privatised' in 1989 and run as a preserved railway operation. It is built to 1ft 11.75in gauge.

The original VoR locomotive was the current number 9. This locomotive was originally numbered 1213 by the GWR in 1923, but was renumbered 9 in 1946, to follow the numbers allocated to the two locomotives built by the GWR to the same design in 1923, which had carried numbers 7 and 8 since their construction.

These three steam locomotives were the only ones to survive in British Rail's ownership after the end of mainline steam traction in August 1968. Under TOPS they were allocated Class 98 and were nominally numbered 98007-98009, but these numbers were never actually carried on the locomotives.

The three locomotives are named as follows:

 7 Owain Glyndwr 8 Llywelyn 9 Prince of Wales 

Registered Steam Locomotives

The Class 98 series has also been used for privately-owned steam locomotives registered to run on the mainline since 1971. The numbers are allocated in the following way:

• Third digit: 0-9 representing the 'Power Class' 0-9 (see here for details)
• Fourth & Fifth digits: The last two digits of the locomotive's original number. If this results in a duplication of an existing number, then the number is increased by 1.

So, as an example, the power class 8P locomotive number 46200 would be allocated 98800, and then power class 8P number 71000 would be allocated 98801.