| PHRENOLOGIST | He bases his findings on an investigation of the headquarters! (12) |
| ANVIL | Smith bases his productions on this (5) |
| GILBERT | Physician who published his findings on terrestrial magnetism in the treatise De Magnete in 1600 (7) |
| REASON | Work by Thomas Paine subtitled Being an Investigation of True and Fabulous Theology (3,3,2,6) |
| THEAGEOF | Work by Thomas Paine subtitled Being an Investigation of True and Fabulous Theology (3,3,2,6) |
| PENTAGON | No 'Agent P' is to be used in defence headquarters! (8) |
| PHILOSOPHY | The rational investigation of the truths and principles of knowledge, reality, and human conduct |
| HABEASCORPUS | Writ for investigation of legality of detention |
| ANALYSIS | Investigation of the component parts which make up the whole (8) |
| PORTISHEAD | Coastal town in North Somerset on the Severn Estuary that is the location of the headquarters of Avon and Somerset Constabulary |
| WOODWARD | Bob _, journalist whose investigation of the Watergate scandal with a fellow Washington Post reporter won the newspaper a Pulitzer Prize in 1973 (8) |
| GENEVA | City in southwest Switzerland, in the Rhone valley; site of the headquarters of the International Red Cross (6) |
| CASEMENT | Name of the headquarters and only airport of the Irish Air Corps (8) |
| SURVEYS | Investigations of the opinions of groups (7) |
| IDIOTIC | Senseless to get beginners in immunology doing investigations of the ear |
| TELLER | He counts the money and may relate his findings (6) |
| HAECKEL | Evolutionary scientist who documented his findings of the mountains and oceans in Kunstformen der Natur (Art Forms in Nature) (7) |
| NYC | Site of the HQ of five major sports |
| PROCONSUL | Governor finding on behalf of overseas agent (9) |
| ANALYST | He breaks down in the course of an investigation |
