1. Sabotage Plan (1938–40) 1
  2. Said, Hussein Ghassan 1, 2
  3. Salter, William 1
  4. Sánchez, Ilich Ramírez (Carlos the Jackal) 1
  5. SAS 1, 2
  6. Scargill, Arthur 1
  7. Schroeder, Frederick Adolphus 1
  8. Schultz, Max 1
  9. Scott, Harold 1
  10. Scott, Russell 1, 2
  12. Secret Agent, The (Joseph Conrad) 1, 2
  13. Secret Intelligence Service 1, 2, 3, 4
  14. secret registry 1
  15. Secret Service Bureau 1
  16. Secret Service Committee (1919) 1
  17. Secret Service Committee (1921) 1
  18. Secret Service Committee (1925) 1
  19. Shaw, George Bernard 1
  20. Shelepin, Alexander 1
  21. Shepherd, William 1, 2
  22. Sherry, Peter 1
  23. Sidney Street siege (1911) 1
  24. Simpson, Colin 1
  25. Sinclair, Hugh 1, 2
  26. Sinn Féin 1, 2, 3, 4, 5, 6
  27. Skardon, Jim 1, 2, 3
  28. Smith, ‘Fergie’ 1, 2
  29. Smith, G. G. (Moonraker) 1, 2, 3
  30. Smith, Michael John 1
  31. Smither, Peter 1
  32. Special Branch Registry 1
  33. Special Demonstration Squad 1, 2
  34. Special Escort Group 1
  35. Special Irish Branch (SIB) 1, 2, 3, 4, 5, 6, 7, 8, 9
    1. renamed Special Branch 1
  36. Special Patrol Group (SPG) 1
  37. Spooner, Reg 1, 2
  38. SS1/SS2 1, 2, 3
  39. Stalin, Joseph 1
  40. state occasions 1
  41. Steinhauer, Gustav 1
  42. Stern Gang 1
  43. STILL LIFE operations 1
  44. ‘Stop the Seventy Tour’ campaign 1
  45. Suffragette movement 1, 2
  46. Sullivan, Pat 1
  47. Sullom Voe bomb plot (1981) 1
  48. surveillance 1
  49. Sweeney, John 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11