I am going to guess it's an EDM ecu from a civic or integra
Edit:
I was somewhat close. After a quick google search I found the the pp4 and pp5 ecu's are honda units sold to Rover in the uk and abroad to run d-series sohc and dohc motors. It appears that the pp4 is functionally the same as a pm6 and the pp5 is close to a pm7.
The pp4 comes from Rover Concerto, 216, and 416 models.
Hope this helps.