45 Anti-Aircraft Brigade was raised in September 1938 at Newport in Wales. It served in Anti-Aircraft Command in South Wales for its entire service. 45 Anti-Aircraft Brigade disappeared from the Order of Battle in December 1944.
Illustrations of the formation badges under which a unit served or supported are given. This is no guarantee that the unit used this formations badge.
| Sep 38 | Raised Newport, Wales |  | 4 Anti-Aircraft Division |
| May 40 | South Wales |  | 5 Anti-Aircraft Division |
| Nov 40 | Cardiff |  | 9 Anti-Aircraft Division |
| Oct 42 | South Wales |  | 3 Anti-Aircraft Group |
| Mar 44 | South Wales | | 4 Anti-Aircraft Group |
| Dec 44 | Disappears from Order of Battle | | |
Order of Battle September 1939
| 77 (Welsh) Anti-Aircraft Regiment (239, 240, 241, 242 Batteries) |
| 6 (Glamorgan) Battalion, Welch Regiment (67 Searchlight Regiment) (450, 451, 452 Companies) |
| 1 (Rifle) Battalion, Monmouthshire Regiment (68 Searchlight Regiment) (453, 454, 455 Companies) |
| 2 (AA Searchlight) Company Carmarthenshire Fortress RE |
Order of Battle August 1940
| 77 (Welsh) Heavy Anti-Aircraft Regiment (239, 240, 241, 242 Batteries) |
| 79 (Herts Yeomanry) Heavy Anti-Aircraft Regiment (246, 247, 248 Batteries) |
| 85 (Tees) Heavy Anti-Aircraft Regiment (174 Battery) |
| 88 Heavy Anti-Aircraft Regiment (283 Battery) |
| 20 Light Anti-Aircraft Regiment (62, 63, 94 Batteries) |
| 34 Light Anti-Aircraft Regiment (64, 65, 92 Batteries) |
| 67 (Welch) Searchlight Regiment (450, 451, 452 Batteries) |
| 77 Searchlight Regiment – Forming |
| 484 (Camarthenshire) Independent Searchlight Battery |
Order of Battle 1940-41
| 77 (Welsh) Heavy Anti-Aircraft Regiment (239, 240, 241, 242 Batteries) |
| 85 (Tees) Heavy Anti-Aircraft Regiment (174, 220 Battery) – Part |
| 88 Heavy Anti-Aircraft Regiment (281, 282, 283 Battery) – Part, Left May 1941 |
| 112 Heavy Anti-Aircraft Regiment (351, 352, 353 Battery) – Joined July 1941 |
| 118 Heavy Anti-Aircraft Regiment (373, 374, 375 Battery) |
| 20 Light Anti-Aircraft Regiment (62, 63, 94, 240 Batteries) |
| 34 Light Anti-Aircraft Regiment (64, 65, 92, 93 Batteries) – Part, Left May 1941 |
| 55 (Devon) Light Anti-Aircraft Regiment (163, 164, 165 Batteries) – On loan from GHQ Reserve |
| 1 Searchlight Regiment (2 Battery) – Part |
| 37 (Tyne Electrical Engineers) Searchlight Regiment (307 Battery) – Part |
| 67 (Welch) Searchlight Regiment (450, 451, 452 Batteries) |
| 8 AA Z Regiment (113, 125, 130, 140 Batteries) |
| 12 AA Z Regiment (101, 111, 124 Batteries) |
Order of Battle 1941-44
| 77 (Welsh) Heavy Anti-Aircraft Regiment (239, 240, 241 Batteries) – Left December 1941 |
| 79 (Herts Yeomanry) Heavy Anti-Aircraft Regiment (246, 247, 398 Batteries) – Left October 1942 |
| 112 Heavy Anti-Aircraft Regiment (351, 352, 353, 380 Batteries) – Left May 1942 |
| 118 Heavy Anti-Aircraft Regiment (275, 373, 374, 375, 399 Batteries) – Unbrigaded April 1943 |
| 166 (Mixed) Heavy Anti-Aircraft Regiment (549, 555, 580 (M) Batteries) – Joined August 1943 |
| 171 (Mixed) Heavy Anti-Aircraft Regiment (474, 496, 569, 580 (M) Batteries) |
| 181 (Mixed) Heavy Anti-Aircraft Regiment (587, 612, 621, 668 (M) Batteries) |
| 20 Light Anti-Aircraft Regiment (62, 63, 244 Batteries) – Left December 1941 |
| 44 Light Anti-Aircraft Regiment (75, 91, 239 Batteries) – Joined Autumn unbrigaded December 1941 |
| 55 (Devon) Light Anti-Aircraft Regiment (163, 164, 165 Batteries) – Left November 1941 |
| 72 Light Anti-Aircraft Regiment (212, 213, 217, 465 Batteries) – Left May 1942 |
| 97 Light Anti-Aircraft Regiment (221, 232, 301, 480 Batteries) – Joined December 1943 |
| 112 (Durham Light Infantry) Light Anti-Aircraft Regiment (364, 365, 366 Batteries) – Joined Summer 1942 |
| 37 (Tyne Electrical Engineers) Searchlight Regiment (307, 308, 348, 349 Batteries) – Joined August 1942 |
| 67 (Welch) Searchlight Regiment (450, 451, 452 Batteries) – Left March 1943 |
| 8 AA Z Regiment (113, 125, 130, 140, 186, 222 Batteries) – Left Autumn 1941 re-joined August 1942 |
| 12 AA Z Regiment (101, 111, 124 Batteries) – Left Autumn 1941 |
| 411 Gun Operations Room |
Order of Battle March-December 1944
| 166 (Mixed) Heavy Anti-Aircraft Regiment (549, 555, 580 (M) Batteries) – Left August 1944 |
| 171 (Mixed) Heavy Anti-Aircraft Regiment (474, 496, 569 (M) Batteries) |
| 181 (Mixed) Heavy Anti-Aircraft Regiment (587, 612, 621 (M) Batteries) |
| 37 (Tyne Electrical Engineers) Searchlight Regiment (307, 308, 348 Batteries) – Left March 1944 |
| 8 AA Z Regiment (113, 125, 130, 140, 186, 222 Batteries) – Left Autumn 1941 re-joined August 1942 |
