Senior Lecturer or Reader

At some universities, these two positions are of equivalent rank with senior lecturer being a teaching-focused position and reader being a research-focused position. But at other universities, a senior lecturer can be promoted to a reader--the more senior rank. In these cases, the senior lecturer can be seen as an associate professor and the reader as a full professor without a chair. At Oxford, a reader is an intermediate position between an associate professor and a professor, however the university has stopped appointing new readers.

https://en.wikipedia.org/wiki/Reader_(academic_rank)

A more accurate analogy:

• Lecturer=Assistant Prof
• Senior Lecturer=Associate Prof
• Reader=Professor
• Professor=Chaired Professor

There are always situations that look like exceptions, of course, but in the humanities at least you really need to have two books in print to get to Reader.

https://www.chronicle.com/forums/index.php?topic=202243.0