ACS1986
Yep, definitely an error. The city centre was recently converted to a "shared space" road layout and that is probably what teh mapper was trying to signify. 
I've retagged the main corporation st/Fishergate stretch as tertiary in line with the rest of the road. Sections of the high street where cars are prohibited entirely or at certain times are tagged as pedestrian with appropriate conditional access tags as necessary. The short stretch between Lune St and Mount St. open to all traffic 24/7 tagged as unclassified. 