diff --git a/app/assets/javascripts/components/option-select.js b/app/assets/javascripts/components/option-select.js
index ccf53709d..a31e1f19f 100644
--- a/app/assets/javascripts/components/option-select.js
+++ b/app/assets/javascripts/components/option-select.js
@@ -61,12 +61,12 @@ window.GOVUK.Modules = window.GOVUK.Modules || {};
     var button = this.$optionSelect.querySelector('.js-container-button')
     button.addEventListener('click', this.toggleOptionSelect.bind(this))
 
-    // Toggle option visibility depending on screen size (min-width: 641px)
-    // and presence of closed options (this.isClosedOnLoadMobile, this.isClosedOnLoad)
+    // Toggle option visibility depending on screen size (min-width: 641px) and 
+    // presence of any 'closed' properties (`data-closed-on-load`, `data-closed-on-load-mobile`)
     if (this.mq.matches) {
-      this.toggleOptionVisibility(this.isClosedOnLoad === 'true')
+      this.toggleVisibility(true)
     } else {
-      this.toggleOptionVisibility(this.hasAnyClosedOptions())
+      this.toggleVisibility(false)
     }
 
     var checkedString = this.checkedString()
@@ -75,18 +75,22 @@ window.GOVUK.Modules = window.GOVUK.Modules || {};
     }
   }
 
-  OptionSelect.prototype.toggleOptionVisibility = function (hasClosedProperty) {
-    if (hasClosedProperty) {
-      this.close()
+  OptionSelect.prototype.toggleVisibility = function (isDesktop) {
+    if (isDesktop) {
+      if (this.isClosedOnLoad === 'true') {
+        this.close()
+      } else {
+        this.setupHeight()
+      }
     } else {
-      this.setupHeight()
+      if (this.isClosedOnLoadMobile === 'true' || this.isClosedOnLoad === 'true') {
+        this.close()
+      } else {
+        this.setContainerHeight(201)
+      }
     }
   }
 
-  OptionSelect.prototype.hasAnyClosedOptions = function () {
-    return this.isClosedOnLoadMobile === 'true' || this.isClosedOnLoad === 'true'
-  }
-
   OptionSelect.prototype.typeFilterText = function (event) {
     event.stopPropagation()
     var ENTER_KEY = 13
@@ -277,7 +281,7 @@ window.GOVUK.Modules = window.GOVUK.Modules || {};
   }
 
   OptionSelect.prototype.setupHeight = function setupHeight () {
-    // get height of option container
+    // get height of option container e.g. 
     var initialOptionContainerHeight = this.$optionsContainer.clientHeight
     // get height of option container ul (containg items)
     var height = this.$optionList.offsetHeight