English mountain hares

While grouse beating here in Derbyshire I invariably see a good number of mountain hares. Am I right in thinking they were introduced here and, if so, when?

The original introductions to the Yorkshire and Derbyshire Pennines date back to about 1880 and the small but isolated population has survived ever since, though with sharp rises and falls in its fortunes.

The hares have been faring well in recent years, largely due to management of the grouse moors where they live. Like grouse, mountain hares favour a mosaic of heather of different ages and heights, so what suits the grouse also helps the hares.

Though the number of days when snow covers the ground are relatively few, these Derbyshire hares still turn white in winter, just like their cousins in Scotland.
By contrast, Ireland’s mountain hares never turn white, but remain a yellowish brown all year round.