diff --git a/DigitalLearningSolutions.Web.Tests/Helpers/ProfessionalRegistrationNumberHelperTests.cs b/DigitalLearningSolutions.Web.Tests/Helpers/ProfessionalRegistrationNumberHelperTests.cs
index a7270f280d..d47a8eeb96 100644
--- a/DigitalLearningSolutions.Web.Tests/Helpers/ProfessionalRegistrationNumberHelperTests.cs
+++ b/DigitalLearningSolutions.Web.Tests/Helpers/ProfessionalRegistrationNumberHelperTests.cs
@@ -107,8 +107,6 @@ public void ValidateProfessionalRegistrationNumber_sets_error_when_hasPrn_is_not
 
         [TestCase(null, ErrorMessagesTestHelper.MissingNumberError)]
         [TestCase("", ErrorMessagesTestHelper.MissingNumberError)]
-        [TestCase("1234", ErrorMessagesTestHelper.LengthError)]
-        [TestCase("1234", ErrorMessagesTestHelper.LengthError)]
         [TestCase("01234_", ErrorMessagesTestHelper.InvalidFormatError)]
         [TestCase("01234 ", ErrorMessagesTestHelper.InvalidFormatError)]
         [TestCase("01234$", ErrorMessagesTestHelper.InvalidFormatError)]
diff --git a/DigitalLearningSolutions.Web.Tests/TestHelpers/ErrorMessagesTestHelper.cs b/DigitalLearningSolutions.Web.Tests/TestHelpers/ErrorMessagesTestHelper.cs
index 7636944e7a..e72983a4a5 100644
--- a/DigitalLearningSolutions.Web.Tests/TestHelpers/ErrorMessagesTestHelper.cs
+++ b/DigitalLearningSolutions.Web.Tests/TestHelpers/ErrorMessagesTestHelper.cs
@@ -4,14 +4,20 @@ namespace DigitalLearningSolutions.Web.Tests.TestHelpers
     public static class ErrorMessagesTestHelper
     {
         public const string InvalidFormatError =
-           "Invalid professional registration number format. " +
-           "Valid formats include: 7 digits (e.g., 1234567), 1–2 letters followed by 6 digits (e.g., AB123456), " +
-           "4–8 digits, an optional 'P' plus 5–6 digits, 'C' or 'P' plus 6 digits, " +
-           "an optional letter plus 5–6 digits, 'L' plus 4–6 digits, " +
-           "or 2 digits followed by a hyphen and 4–5 alphanumeric characters (e.g., 12-AB123).";
+            @"The format you entered isn’t recognised. Please check and try again.
+            <br>Valid formats include:
+            <ul>
+                <li>7 digits - example, 1234567</li>
+                <li>1–2 letters followed by 6 digits - example, AB123456</li>
+                <li>‘P’ followed by 5–6 digits - example, P12345, P123456</li>
+                <li>‘C’ or ‘P’ followed by 6 digits - example, C123456, P123456</li>
+                <li>Optional letter followed by 5–6 digits - example, A12345, B123456</li>
+                <li>‘L’ followed by 4–6 digits - example, L1234, L123456</li>
+                <li>2 digits, hyphen, then 4–5 alphanumeric characters - example, 12-AB123</li>
+            </ul>";
 
         public const string MissingNumberError = "Enter a professional registration number";
-        public const string LengthError = "Professional registration number must be between 5 and 20 characters";
+        public const string LengthError = "Professional registration number must be between 4 and 8 characters";
 
     }
 }
diff --git a/DigitalLearningSolutions.Web/Helpers/ProfessionalRegistrationNumberHelper.cs b/DigitalLearningSolutions.Web/Helpers/ProfessionalRegistrationNumberHelper.cs
index 130c8d52b6..a667a1f597 100644
--- a/DigitalLearningSolutions.Web/Helpers/ProfessionalRegistrationNumberHelper.cs
+++ b/DigitalLearningSolutions.Web/Helpers/ProfessionalRegistrationNumberHelper.cs
@@ -1,6 +1,8 @@
 namespace DigitalLearningSolutions.Web.Helpers
 {
+
     using Microsoft.AspNetCore.Mvc.ModelBinding;
+    using System.Text;
     using System.Text.RegularExpressions;
 
     public class ProfessionalRegistrationNumberHelper
@@ -39,28 +41,29 @@ public static void ValidateProfessionalRegistrationNumber(
                 modelState.AddModelError("ProfessionalRegistrationNumber", "Enter a professional registration number");
                 return;
             }
-
-            if (prn.Length < 5 || prn.Length > 20)
-            {
-                modelState.AddModelError(
-                    "ProfessionalRegistrationNumber",
-                    "Professional registration number must be between 5 and 20 characters"
-                );
-            }
-
-           const string pattern = @"^(\d{7}|[A-Za-z]{1,2}\d{6}|\d{4,8}|P?\d{5,6}|[C|P]\d{6}|[A-Za-z]?\d{5,6}|L\d{4,6}|\d{2}-[A-Za-z\d]{4,5})$";
+            const string pattern = @"^(\d{7}|[A-Za-z]{1,2}\d{6}|\d{4,8}|P?\d{5,6}|[C|P]\d{6}|[A-Za-z]?\d{5,6}|L\d{4,6}|\d{2}-[A-Za-z\d]{4,5})$";
             var rg = new Regex(pattern, RegexOptions.IgnoreCase);
             if (!rg.Match(prn).Success)
             {
                 modelState.AddModelError(
                     "ProfessionalRegistrationNumber",
-                   "Invalid professional registration number format. " +
-        "Valid formats include: 7 digits (e.g., 1234567), 1–2 letters followed by 6 digits (e.g., AB123456), " +
-        "4–8 digits, an optional 'P' plus 5–6 digits, 'C' or 'P' plus 6 digits, " +
-        "an optional letter plus 5–6 digits, 'L' plus 4–6 digits, " +
-        "or 2 digits followed by a hyphen and 4–5 alphanumeric characters (e.g., 12-AB123)."
+                 GetProfessionalRegistrationNumberErrorMessage()
                 );
             }
         }
+        public static string GetProfessionalRegistrationNumberErrorMessage()
+        {
+            return @"The format you entered isn’t recognised. Please check and try again.
+            <br>Valid formats include:
+            <ul>
+                <li>7 digits - example, 1234567</li>
+                <li>1–2 letters followed by 6 digits - example, AB123456</li>
+                <li>‘P’ followed by 5–6 digits - example, P12345, P123456</li>
+                <li>‘C’ or ‘P’ followed by 6 digits - example, C123456, P123456</li>
+                <li>Optional letter followed by 5–6 digits - example, A12345, B123456</li>
+                <li>‘L’ followed by 4–6 digits - example, L1234, L123456</li>
+                <li>2 digits, hyphen, then 4–5 alphanumeric characters - example, 12-AB123</li>
+            </ul>";
+        }
     }
 }
diff --git a/DigitalLearningSolutions.Web/Views/Shared/_EditRegistrationNumber.cshtml b/DigitalLearningSolutions.Web/Views/Shared/_EditRegistrationNumber.cshtml
index d50f11c819..d0ffd7d154 100644
--- a/DigitalLearningSolutions.Web/Views/Shared/_EditRegistrationNumber.cshtml
+++ b/DigitalLearningSolutions.Web/Views/Shared/_EditRegistrationNumber.cshtml
@@ -17,6 +17,11 @@
 
   var subject = Model.IsSelfRegistrationOrEdit ? "you" : "they";
   var capitalisedSubject = Model.IsSelfRegistrationOrEdit ? "You" : "They";
+    var professionalRegistrationNumberError = ViewData.ModelState["ProfessionalRegistrationNumber"]?.Errors.FirstOrDefault()?.ErrorMessage;
+    if (ViewData.ModelState.ContainsKey("ProfessionalRegistrationNumber"))
+    {
+        ViewData.ModelState["ProfessionalRegistrationNumber"].Errors.Clear();
+    }
 }
 
 <input type="hidden" asp-for="IsSelfRegistrationOrEdit" />
@@ -53,7 +58,7 @@
           No
         </label>
       </div>
-
+           
       <div class="nhsuk-radios__item">
         <input name="@nameof(Model.HasProfessionalRegistrationNumber)"
                class="nhsuk-radios__input"
@@ -66,9 +71,16 @@
           Yes
         </label>
       </div>
-      <div class="nhsuk-radios__conditional @(optionYesSelected ? " " : " nhsuk-radios__conditional--hidden") @(professionalRegNumberErrorHasOccurred ? "form-group-wrapper--error" : "" )"
+      <div class="nhsuk-radios__conditional"
            id="@professionalRegConditionalId">
-        <vc:text-input asp-for="@nameof(Model.ProfessionalRegistrationNumber)"
+                @if (professionalRegistrationNumberError != null)
+                {
+                    <span class="nhsuk-error-message" id="ProfessionalRegistrationNumber-error">
+                        <span class="nhsuk-u-visually-hidden">Error:</span>
+                        @Html.Raw(professionalRegistrationNumberError)
+                    </span>
+                }
+                      <vc:text-input asp-for="@nameof(Model.ProfessionalRegistrationNumber)"
                        label="Professional Registration Number"
                        populate-with-current-value="true"
                        type="text"
diff --git a/DigitalLearningSolutions.Web/Views/TrackingSystem/Delegates/EditDelegate/Index.cshtml b/DigitalLearningSolutions.Web/Views/TrackingSystem/Delegates/EditDelegate/Index.cshtml
index 654379181a..438175861c 100644
--- a/DigitalLearningSolutions.Web/Views/TrackingSystem/Delegates/EditDelegate/Index.cshtml
+++ b/DigitalLearningSolutions.Web/Views/TrackingSystem/Delegates/EditDelegate/Index.cshtml
@@ -15,7 +15,10 @@
   <div class="nhsuk-grid-column-full">
     @if (errorHasOccurred)
     {
-      <vc:error-summary order-of-property-names="@(new[] {
+            var professionalRegistrationNumberError = ViewData.ModelState["ProfessionalRegistrationNumber"]?.Errors.FirstOrDefault();
+            if (professionalRegistrationNumberError == null)
+            {
+                <vc:error-summary order-of-property-names="@(new[] {
                                                    nameof(Model.FirstName),
                                                    nameof(Model.LastName),
                                                    nameof(Model.CentreSpecificEmail),
@@ -28,6 +31,23 @@
                                                    nameof(Model.Answer4),
                                                    nameof(Model.Answer5),
                                                    nameof(Model.Answer6) })" />
+            }
+            if (professionalRegistrationNumberError != null)
+            {
+                <div class="nhsuk-error-summary" aria-labelledby="error-summary-title" role="alert" tabindex="-1">
+                    <h2 class="nhsuk-error-summary__title" id="error-summary-title">
+                        There is a problem
+                    </h2>
+                    <div class="nhsuk-error-summary__body">
+                        <span class="nhsuk-error-message" id="ProfessionalRegistrationNumber-error">
+                            <span class="nhsuk-u-visually-hidden">Error:</span> <span class="nhsuk-error-message" id="ProfessionalRegistrationNumber-error">
+                                <span class="nhsuk-u-visually-hidden">Error:</span>
+                                @Html.Raw(professionalRegistrationNumberError.ErrorMessage)
+                            </span>
+                        </span>
+                    </div>
+                </div>
+            }
     }
 
     <h1 class="nhsuk-heading-xl">Edit delegate details</h1>