Limestone pavements can occur where ever the soil has been removed to reveal the weathered limestone bedrock beneath. Dissolution of limestone beneath a soil cover will enlarge the joints and fissures to create the classic clints and grikes, but they are only revealed when the soil is removed. The most common cause for soil loss is glacial activity, but any soil erosion can do the trick. In the example at Backwell, it is the local volunteer group who removed the soil cover! If you removed the soil from many limestone areas you would see much the same thing, especially in flat or gently dipping limestones. In southern England, exposed limestone pavements such as these will rapidly be covered over by vegetation, and the fissures infilled with soil, but in upland areas of northern England, the climate is less forgiving and that, coupled with overgrazing will keep them exposed.
The ice never got as far as Mendip, even in the Anglian. It just about impinged on what is now the coast near Clevedon, but there is no evidence for any glacial activity on Mendip. Plenty of examples of superimposed drainage and periglacial activity, but no ice.