diff --git a/pages/_document.js b/pages/_document.js
index cf1d68b7..0be14036 100644
--- a/pages/_document.js
+++ b/pages/_document.js
@@ -24,9 +24,9 @@ class MyDocument extends Document {
         const cookieObj = ctx.req.cookies.CookiePolicy || {};
 
         //console.log("useGATracking: ", useGATracking);
-        setCookie(ctx, "pedw_locale", ctx.locale, {
-            path: "/",
-        });
+        // setCookie(ctx, "pedw_locale", ctx.locale, {
+        //     path: "/",
+        // });
 
         const headers = ctx.req?.headers;
         const generatedNonce = headers?.["x-nonce"];
@@ -84,7 +84,7 @@ class MyDocument extends Document {
                                     __html:
                                         "window.switchDomain = '" +
                                         process.env.I18N_DOMAIN +
-                                        "'",
+                                        "'"
                                 }}
                             />
                             <script
@@ -93,7 +93,7 @@ class MyDocument extends Document {
                                     __html:
                                         "window.apiRoot = '" +
                                         process.env.API_ROOT +
-                                        "'",
+                                        "'"
                                 }}
                             />
                         </>
diff --git a/pages/api/auth/[...nextauth].js b/pages/api/auth/[...nextauth].js
index 9e017930..09ffa396 100644
--- a/pages/api/auth/[...nextauth].js
+++ b/pages/api/auth/[...nextauth].js
@@ -37,11 +37,12 @@ const appendParamsAndPathToNewUrl = (fromUrl, toUrl) => {
     return toUrlObj.toString();
 };
 
-const resolveRequestLocale = (req) =>
-    req?.query?.locale ||
-    req?.body?.locale ||
-    req?.cookies?.pedw_locale ||
-    "en";
+const resolveRequestLocale = (req) => {
+    const locale =
+        req?.body?.locale || req?.query?.locale || req?.cookies?.pedw_locale;
+
+    return locale === "cy" ? "cy" : "en";
+};
 
 const resolveCrmLocale = async (email) => {
     if (!email) return null;
diff --git a/pages/auth/signin.js b/pages/auth/signin.js
index 2de256c8..2767cffa 100644
--- a/pages/auth/signin.js
+++ b/pages/auth/signin.js
@@ -21,7 +21,7 @@ const SignIn = (props) => {
 
         try {
             const email = String(event.target.email.value || "").trim();
-            const currentLocale = lang || "en";
+            const currentLocale = lang === "cy" ? "cy" : "en";
 
             const response = await fetch("/api/auth/resolve-locale", {
                 method: "POST",
@@ -48,9 +48,10 @@ const SignIn = (props) => {
             });
 
             event.target.callbackUrl.value = url.toString();
+            event.target.locale.value = resolvedLocale;
             event.target.submit();
         } catch (error) {
-            const fallbackLocale = lang || "en";
+            const fallbackLocale = lang === "cy" ? "cy" : "en";
             const url = new URL(event.target.callbackUrl.value);
             url.searchParams.set("locale", fallbackLocale);
 
@@ -59,6 +60,7 @@ const SignIn = (props) => {
             });
 
             event.target.callbackUrl.value = url.toString();
+            event.target.locale.value = fallbackLocale;
             event.target.submit();
         }
     };
@@ -118,6 +120,16 @@ const SignIn = (props) => {
                                                                     callbackUrl
                                                                 }
                                                             />
+                                                            <input
+                                                                name="locale"
+                                                                type="hidden"
+                                                                defaultValue={
+                                                                    lang ===
+                                                                    "cy"
+                                                                        ? "cy"
+                                                                        : "en"
+                                                                }
+                                                            />
 
                                                             <label
                                                                 className="govuk-label"
diff --git a/pages/auth/verify-request.js b/pages/auth/verify-request.js
index d86db3eb..3d59bf99 100644
--- a/pages/auth/verify-request.js
+++ b/pages/auth/verify-request.js
@@ -45,7 +45,10 @@ const SignIn = (props) => {
                         <div className="govuk-grid-row">
                             <div className="govuk-grid-column-two-thirds govuk-body">
                                 {" "}
-                                <Link href="/" legacyBehavior>
+                                <Link
+                                    href="/"
+                                    locale={lang === "cy" ? "cy" : "en"}
+                                >
                                     {t("auth:auth-return-home-link-label")}
                                 </Link>
                             </div>
@@ -61,7 +64,7 @@ const SignIn = (props) => {
 export async function getServerSideProps(context) {
     const csrfToken = await getCsrfToken(context);
     return {
-        props: { csrfToken, locale: context.locale },
+        props: { csrfToken, locale: context.locale }
     };
 }