A total of seven actors who have played major characters on 'Primeval' (Lucy Brown, James Murray, Andrew-Lee Potts, Juliet Aubrey, Ciaran McMenamin, Laila Rouass and Anton Lesser) have also appeared in the popular TV series 'Midsomer Murders'.
The final 13 episodes, combined series 4 and 5, were actually shot at various locations within the Republic of Ireland, mostly around the Dublin-Wicklow area, some with none to major digital set dressing enhancement. The city wall map in the office, in Series 4 and 5, is actually Dublin City, turned upside down.
The trivia items below may give away important plot points.
At the end of the last episode in Season one, it is revealed that Nick Cutter's trip back in time to the Permian Period changed the "present", with only he knowing the truth. The character Claudia Brown no longer exists, but has now morphed into Jenny Lewis (also played by Lucy Brown) and there is now the existence of the ARC - the Anomaly Research Centre. The remainder of the seasons play out in this altered time-line.