There are stone circle "gaps" elsewhere in the country. Where I live now in Gloucestershire, also Worcestershire and Herefordshire, there are no circles - you have to go into west into Wales (Four Stones), or SW to Stanton Drew, SE to Avebury, east to Rollright, north to Mitchell's Fold. I think it may be a lot to do with farming from the middle ages on, particularly where there is a lot of enclosure.

Similarly in Yorkshire, there are some circles in the North and West Ridings, but nothing in the East Riding, where it's mainly barrows (and the Rudston Monolith - perhaps that makes up for the lack of other standing stones!). The circles and standing stones are on the moors, East Riding is all arable (and flat).