In reply to ColinVern:
Loads of cracks on gritstone crags, natural & quarried. Many are often accompanied by other features (obviously the walls either side, & the crack edges as laybacks/sidepulls, & horizontal breaks etc) but you aren't compelled to use them. How you climb a crack depends on your preferred technique/strengths. Go and try Goliaths Groove or head straight for Rays Roof (not a serious recommendation!!). Plenty more at Stanage, Millstone, Hen Cloud, et al. Nothing as big as in other areas/countries, but enough for you to develop your skills whilst saving up for American Adventures