A new mixed-field imaging system has been constructed at Lancaster University using the principles of collimation and back projection to passively locate and assess sources of neutron and gamma-ray radiation. The system was set up at the University of Manchester where three radiation sources: 252Cf, a lead-shielded 241Am/Be and a 22Na source were imaged. Real-time discrimination was used to find the respective components of the neutron and gamma-ray fields detected by a single EJ-301 liquid scintillator, allowing separate images of neutron and gamma-ray emitters to be formed. 252Cf and 22Na were successfully observed and located in the gamma-ray image; however, the 241Am/Be was not seen owing to surrounding lead shielding. The 252Cf and 241Am/Be neutron sources were seen clearly in the neutron image, demonstrating the advantage of this mixed-field technique over a gamma-ray-only image where the 241Am/Be source would have gone undetected.