diff --git a/app/assets/javascripts/application.js b/app/assets/javascripts/application.js
index 2e2a4959cc..67e053b21c 100644
--- a/app/assets/javascripts/application.js
+++ b/app/assets/javascripts/application.js
@@ -1,6 +1,15 @@
 /* global $ */
 /* global GOVUK */
 
+// Warn about using the kit in production
+if (
+  window.sessionStorage && window.sessionStorage.getItem('prototypeWarning') !== 'false' &&
+  window.console && window.console.info
+) {
+  window.console.info('GOV.UK Prototype Kit - do not use for production')
+  window.sessionStorage.setItem('prototypeWarning', true)
+}
+
 function ShowHideContent () {
   var self = this
 
@@ -65,6 +74,7 @@ function ShowHideContent () {
       }
     })
   }
+
   self.showHideCheckboxToggledContent = function () {
     $(".block-label input[type='checkbox']").each(function () {
       var $checkbox = $(this)