It's my understanding that B6 turnouts were a post-grouping design and that the Midland would have used 1 in 6 common crossings together with 12 ft switches, either loose heeled or after about 1900 ish possibly sprung heeled. I'm not an expert on track, though, and depend for advice on Crimson Rambler, who has made a study of Midland trackwork. Maybe contacting him would be worthwhile?

Dave