diff --git a/assets/localisations/autocomplete/eng-US.json b/assets/localisations/autocomplete/eng-GB.json
similarity index 100%
rename from assets/localisations/autocomplete/eng-US.json
rename to assets/localisations/autocomplete/eng-GB.json
diff --git a/assets/localisations/commands/eng-US.json b/assets/localisations/commands/eng-GB.json
similarity index 100%
rename from assets/localisations/commands/eng-US.json
rename to assets/localisations/commands/eng-GB.json
diff --git a/assets/localisations/entry/eng-US.json b/assets/localisations/entry/eng-GB.json
similarity index 100%
rename from assets/localisations/entry/eng-US.json
rename to assets/localisations/entry/eng-GB.json
diff --git a/assets/localisations/events/eng-US.json b/assets/localisations/events/eng-GB.json
similarity index 100%
rename from assets/localisations/events/eng-US.json
rename to assets/localisations/events/eng-GB.json
diff --git a/assets/localisations/interactions/eng-US.json b/assets/localisations/interactions/eng-GB.json
similarity index 100%
rename from assets/localisations/interactions/eng-US.json
rename to assets/localisations/interactions/eng-GB.json
diff --git a/assets/localisations/languages/eng-US.json b/assets/localisations/languages/eng-GB.json
similarity index 100%
rename from assets/localisations/languages/eng-US.json
rename to assets/localisations/languages/eng-GB.json
diff --git a/assets/localisations/licences/eng-US.json b/assets/localisations/licences/eng-GB.json
similarity index 100%
rename from assets/localisations/licences/eng-US.json
rename to assets/localisations/licences/eng-GB.json
diff --git a/assets/localisations/modals/eng-US.json b/assets/localisations/modals/eng-GB.json
similarity index 100%
rename from assets/localisations/modals/eng-US.json
rename to assets/localisations/modals/eng-GB.json
diff --git a/assets/localisations/parameters/eng-US.json b/assets/localisations/parameters/eng-GB.json
similarity index 100%
rename from assets/localisations/parameters/eng-US.json
rename to assets/localisations/parameters/eng-GB.json
diff --git a/assets/localisations/policies/eng-US.json b/assets/localisations/policies/eng-GB.json
similarity index 100%
rename from assets/localisations/policies/eng-US.json
rename to assets/localisations/policies/eng-GB.json
diff --git a/assets/localisations/roles/eng-US.json b/assets/localisations/roles/eng-GB.json
similarity index 100%
rename from assets/localisations/roles/eng-US.json
rename to assets/localisations/roles/eng-GB.json
diff --git a/assets/localisations/rules/eng-US.json b/assets/localisations/rules/eng-GB.json
similarity index 100%
rename from assets/localisations/rules/eng-US.json
rename to assets/localisations/rules/eng-GB.json
diff --git a/assets/localisations/services/eng-US.json b/assets/localisations/services/eng-GB.json
similarity index 100%
rename from assets/localisations/services/eng-US.json
rename to assets/localisations/services/eng-GB.json
diff --git a/assets/localisations/time/eng-US.json b/assets/localisations/time/eng-GB.json
similarity index 100%
rename from assets/localisations/time/eng-US.json
rename to assets/localisations/time/eng-GB.json
diff --git a/assets/localisations/words/eng-US.json b/assets/localisations/words/eng-GB.json
similarity index 100%
rename from assets/localisations/words/eng-US.json
rename to assets/localisations/words/eng-GB.json
diff --git a/source/constants/defaults.ts b/source/constants/defaults.ts
index 9befcf73a..4ba22226c 100644
--- a/source/constants/defaults.ts
+++ b/source/constants/defaults.ts
@@ -4,13 +4,13 @@ import type { Locale, LocalisationLanguage } from "logos:constants/languages/loc
 import type { TranslationLanguage } from "logos:constants/languages/translation";
 import type { RateLimit, TimeStruct } from "logos/models/guild";
 
-const FEATURE_LOCALE: Locale = "eng-US";
+const FEATURE_LOCALE: Locale = "eng-GB";
 const FEATURE_LANGUAGE: FeatureLanguage = "English";
-const LEARNING_LOCALE: Locale = "eng-US";
-const LEARNING_LANGUAGE: LearningLanguage = "English/American";
-const LOCALISATION_LOCALE: Locale = "eng-US";
-const LOCALISATION_LANGUAGE: LocalisationLanguage = "English/American";
-const TRANSLATION_LANGUAGE: TranslationLanguage = "English/American";
+const LEARNING_LOCALE: Locale = "eng-GB";
+const LEARNING_LANGUAGE: LearningLanguage = "English/British";
+const LOCALISATION_LOCALE: Locale = "eng-GB";
+const LOCALISATION_LANGUAGE: LocalisationLanguage = "English/British";
+const TRANSLATION_LANGUAGE: TranslationLanguage = "English/British";
 
 const COMMAND_RATE_LIMIT: RateLimit = { uses: 5, within: [10, "second"] };
 const REPORT_RATE_LIMIT: RateLimit = { uses: 50, within: [1, "day"] };
diff --git a/test/source/constants/languages/learning.spec.ts b/test/source/constants/languages/learning.spec.ts
index bbc477470..0179dcd67 100644
--- a/test/source/constants/languages/learning.spec.ts
+++ b/test/source/constants/languages/learning.spec.ts
@@ -27,14 +27,14 @@ describe("isLocale()", () => {
 
 describe("getLocaleByLanguage()", () => {
 	it("returns the language corresponding to the passed learning locale.", () => {
-		expect(getLogosLocaleByLanguage("English/American")).to.equal("eng-US");
+		expect(getLogosLocaleByLanguage("English/British")).to.equal("eng-GB");
 		expect(getLogosLocaleByLanguage("German")).to.equal("deu");
 	});
 });
 
 describe("getWiktionaryLanguageName()", () => {
 	it("returns the Wiktionary name for the learning language if available.", () => {
-		expect(getWiktionaryLanguageName("English/American")).to.equal("English");
+		expect(getWiktionaryLanguageName("English/British")).to.equal("English");
 		expect(getWiktionaryLanguageName("Norwegian/Bokmal")).to.equal("Norwegian Bokmål");
 	});
 });
diff --git a/test/source/constants/languages/localisation.spec.ts b/test/source/constants/languages/localisation.spec.ts
index 68990a144..f580c0da2 100644
--- a/test/source/constants/languages/localisation.spec.ts
+++ b/test/source/constants/languages/localisation.spec.ts
@@ -34,7 +34,7 @@ describe("isLogosLanguage()", () => {
 
 describe("isLogosLocale()", () => {
 	it("returns true if the passed locale is supported by Logos.", () => {
-		expect(isLogosLocale("eng-US")).to.be.true; // American English
+		expect(isLogosLocale("eng-GB")).to.be.true; // British English
 	});
 
 	it("returns false if the passed locale is not supported by Logos.", () => {
@@ -44,21 +44,21 @@ describe("isLogosLocale()", () => {
 
 describe("getDiscordLocaleByLanguage()", () => {
 	it("returns the language corresponding to the passed locale.", () => {
-		expect(getDiscordLocaleByLanguage("English/American")).to.equal("en-US");
+		expect(getDiscordLocaleByLanguage("English/British")).to.equal("en-GB");
 		expect(getDiscordLocaleByLanguage("German")).to.equal("de");
 	});
 });
 
 describe("getLogosLocaleByLanguage()", () => {
 	it("returns the language corresponding to the passed locale.", () => {
-		expect(getLogosLocaleByLanguage("English/American")).to.equal("eng-US");
+		expect(getLogosLocaleByLanguage("English/British")).to.equal("eng-GB");
 		expect(getLogosLocaleByLanguage("German")).to.equal("deu");
 	});
 });
 
 describe("getDiscordLanguageByLocale()", () => {
 	it("returns the language corresponding to the passed locale if the locale is valid.", () => {
-		expect(getDiscordLanguageByLocale("en-US")).to.equal("English/American");
+		expect(getDiscordLanguageByLocale("en-GB")).to.equal("English/British");
 		expect(getDiscordLanguageByLocale("ro")).to.equal("Romanian");
 	});
 
@@ -70,7 +70,7 @@ describe("getDiscordLanguageByLocale()", () => {
 
 describe("getLogosLanguageByLocale()", () => {
 	it("returns the language corresponding to the passed locale.", () => {
-		expect(getLogosLanguageByLocale("eng-US")).to.equal("English/American");
+		expect(getLogosLanguageByLocale("eng-GB")).to.equal("English/British");
 		expect(getLogosLanguageByLocale("ron")).to.equal("Romanian");
 	});
 });