Mirren was ,in the early 90s IIRC and yes this is a prequel with another woman. Mirren is a great actress and she goes through the trials and tribulations of being a woman detective in an age where that was unusual. This new one is going the same so it looks like that will be the theme of all prime suspects. maybe we’ll have others, bit they need to be dated because nowadays the only new group would be trannies.
That is one good thing about the period piece detective series: less of the modern PC baggage.