 Kieron MooreCmdr. Michael Haydon | Cmdr. Michael Haydon |
 Lois MaxwellKim Hamilton | Kim Hamilton |
 Donald WolfitProf. Merrity | Prof. Merrity |
 Bryan ForbesJimmy Wheeler | Jimmy Wheeler |
 Jimmy HanleyLarry Noble | Larry Noble |
 Barry KeeganLefty | Lefty |
 Walter HuddProfessor Blandford | Professor Blandford |
 Donald GrayCaptain Ross | Captain Ross |
| TThea GregoryBarbara Noble | Barbara Noble |
| SShirley LawrenceEllen | Ellen |
| PPeter NeilTony | Tony |
| RRyck RydonReporter | Reporter |
 Ronan O'CaseyReporter | Reporter |
 Robert O'NeilReporter | Reporter |
 Alan GiffordColonel Galloway | Colonel Galloway |
| CCharles RichardsonGeneral Barnett | General Barnett |
 Carl JaffeProfessor Bechstein | Professor Bechstein |
| LLeonard SharpThomas the Watchman (uncredited) | Thomas the Watchman (uncredited) |
| PPaul BeradiReporter (uncredited) | Reporter (uncredited) |
| PPatrick HalpinReporter (uncredited) | Reporter (uncredited) |
| TTerry RandallReporter (uncredited) | Reporter (uncredited) |
 Bill NagyReporter (uncredited) | Reporter (uncredited) |
| TTerry RandallReporter (uncredited) | Reporter (uncredited) |
| JJohn WilderReporter (uncredited) | Reporter (uncredited) |
| JJohnny WyneReporter (uncredited) | Reporter (uncredited) |
 Trevor ReidSimmons the Technician (uncredited) | Simmons the Technician (uncredited) |
 Bernard BresslawTechnician (uncredited) | Technician (uncredited) |
 Alastair HunterTechnician (uncredited) | Technician (uncredited) |
| JJane DoreYoung Girl (uncredited) | Young Girl (uncredited) |
| FFrank SiemanGatekeeper (uncredited) | Gatekeeper (uncredited) |
