Towards the end of the 19th century, the age of the single-driver locomotive was obsolete because the trains, which had become heavier, required pulling forces that could no longer be provided by one drive axle alone.

When steam sanding was invented by James Gresham in 1885[4] this improved the traction of the driving wheels enough that singles were once again a practical design.

This required a locomotive that was powerful,[ii] with the ability to run at high speeds, but only of modest tractive effort.

The use of inside cylinders also reduced the rocking couple,[iv] which could become a problem for outside-cylindered locomotives with short wheelbases at high speed.

[6] Between 1887 and 1900, Johnson had no fewer than 95 single locomotives built by the railway's own workshops in Derby, which differed slightly in structural details.