Don't know about 'ropey' production quality. Cheap certainly- most Hammer films were made in tiny studios in Bray. Most used the same sets, but the cinematography, especially the ones shot by Freddie Francis, was as good as anything American. The 'grittiness, immediacy and atmosphere' is down to the presence of some very good film makers, rather than low production values. Although, as one critic cruelly said' Hammer films are horrors made by men who 'do their gardens at the week end'.