Raymond wrote 5 books in his Factory series starring an unnamed detective. (Not to be confused with Bill Pronzini’s Nameless!)
1. He Died with His Eyes Open (1976)
2. The Devil's Home on Leave (1985)
3. How the Dead Live (1986)
4. I Was Dora Suarez (1990)
5. Dead Man Upright (1993)
Derek Raymond died in 1994. I still haven’t read him yet.
There’s an interesting piece from 2013 in The New York Review of Books on a couple of the books and the series in general here. I’ve only skim read it in case it spoils things for me!
He Died With His Eyes Open (1976)
The first of the "Factory" series of bleak, atmospheric and subversive crime novels. A boozed-out tramp found under a bush in West London has been systematically butchered. The awesome depths of violent passion that the victim must have inspired fascinates the detective sergeant put on the case.
I Was Dora Suarez (1990)
One of the "Factory" series of bleak, atmospheric and subversive crime novels. Next door to the bloodied remains of London prostitute Dora Suarez lies the broken body of an 86-year-old widow, and a mile away the brains of a sleazy West End racketeer are found adorning the walls of his dining room.