diff --git a/admin/blocks.php b/admin/blocks.php
index 17b035090ec1f..b4fa84147a974 100644
--- a/admin/blocks.php
+++ b/admin/blocks.php
@@ -12,6 +12,8 @@
     $hide     = optional_param('hide', 0, PARAM_INT);
     $show     = optional_param('show', 0, PARAM_INT);
     $delete   = optional_param('delete', 0, PARAM_INT);
+    $unprotect = optional_param('unprotect', 0, PARAM_INT);
+    $protect = optional_param('protect', 0, PARAM_INT);
 
 /// Print headings
 
@@ -24,6 +26,9 @@
     $strcourses = get_string('blockinstances', 'admin');
     $strname = get_string('name');
     $strshowblockcourse = get_string('showblockcourse');
+    $strprotecthdr = get_string('blockprotect', 'admin'). $OUTPUT->help_icon('blockprotect','admin');
+    $strprotect = get_string('blockprotect', 'admin');
+    $strunprotect = get_string('blockunprotect', 'admin');
 
 /// If data submitted, then process and store.
 
@@ -43,6 +48,36 @@
         admin_get_root(true, false);  // settings not required - only pages
     }
 
+    if (!isset($CFG->undeletableblocktypes) || (!is_array($CFG->undeletableblocktypes) && !is_string($CFG->undeletableblocktypes))) {
+        $undeletableblocktypes = array('navigation', 'settings');
+    } else if (is_string($CFG->undeletableblocktypes)) {
+        $undeletableblocktypes = explode(',', $CFG->undeletableblocktypes);
+    } else {
+        $undeletableblocktypes = $CFG->undeletableblocktypes;
+    }
+
+    if (!empty($protect) && confirm_sesskey()) {
+        if (!$block = $DB->get_record('block', array('id'=>$protect))) {
+            print_error('blockdoesnotexist', 'error');
+        }
+        if (!in_array($block->name, $undeletableblocktypes)) {
+            $undeletableblocktypes[] = $block->name;
+            set_config('undeletableblocktypes', implode(',', $undeletableblocktypes));
+        }
+        admin_get_root(true, false);  // settings not required - only pages
+    }
+
+    if (!empty($unprotect) && confirm_sesskey()) {
+        if (!$block = $DB->get_record('block', array('id'=>$unprotect))) {
+            print_error('blockdoesnotexist', 'error');
+        }
+        if (in_array($block->name, $undeletableblocktypes)) {
+            $undeletableblocktypes = array_diff($undeletableblocktypes, array($block->name));
+            set_config('undeletableblocktypes', implode(',', $undeletableblocktypes));
+        }
+        admin_get_root(true, false);  // settings not required - only pages
+    }
+
     if (!empty($delete) && confirm_sesskey()) {
         echo $OUTPUT->header();
         echo $OUTPUT->heading($strmanageblocks);
@@ -114,8 +149,8 @@
 
     $table = new flexible_table('admin-blocks-compatible');
 
-    $table->define_columns(array('name', 'instances', 'version', 'hideshow', 'delete', 'settings'));
-    $table->define_headers(array($strname, $strcourses, $strversion, $strhide.'/'.$strshow, $strdelete, $strsettings));
+    $table->define_columns(array('name', 'instances', 'version', 'hideshow', 'undeletable', 'delete', 'settings'));
+    $table->define_headers(array($strname, $strcourses, $strversion, $strhide.'/'.$strshow, $strprotecthdr, $strdelete, $strsettings));
     $table->define_baseurl($CFG->wwwroot.'/'.$CFG->admin.'/blocks.php');
     $table->set_attribute('class', 'compatibleblockstable blockstable generaltable');
     $table->setup();
@@ -191,12 +226,23 @@
             $version = "$block->version ($plugin->version)";
         }
 
+        if (!$blockobject) {
+            // ignore
+            $undeletable = '';
+        } else if (in_array($blockname, $undeletableblocktypes)) {
+            $undeletable = '<a href="blocks.php?unprotect='.$blockid.'&amp;sesskey='.sesskey().'" title="'.$strunprotect.'">'.
+                       '<img src="'.$OUTPUT->pix_url('t/unlock') . '" class="icon" alt="'.$strunprotect.'" /></a>';
+        } else {
+            $undeletable = '<a href="blocks.php?protect='.$blockid.'&amp;sesskey='.sesskey().'" title="'.$strprotect.'">'.
+                       '<img src="'.$OUTPUT->pix_url('t/unlock_gray') . '" class="icon" alt="'.$strprotect.'" /></a>';
+        }
 
         $table->add_data(array(
             '<span'.$class.'>'.$strblockname.'</span>',
             $blocklist,
             '<span'.$class.'>'.$version.'</span>',
             $visible,
+            $undeletable,
             $delete,
             $settings
         ));
diff --git a/config-dist.php b/config-dist.php
index 61c4e20bc004b..4ca2b728e029f 100644
--- a/config-dist.php
+++ b/config-dist.php
@@ -208,11 +208,6 @@
 // These blocks are used when no other default setting is found.
 //      $CFG->defaultblocks = 'participants,activity_modules,search_forums,admin,course_list:news_items,calendar_upcoming,recent_activity';
 //
-// The blocks in this list will be protected from deletion, and this is primarily
-// used to protect the navigation and settings blocks which can be very hard to
-// get back if accidentally delete.
-//      $CFG->undeletableblocktypes = 'navigation,settings';
-//
 // You can specify a different class to be created for the $PAGE global, and to
 // compute which blocks appear on each page. However, I cannot think of any good
 // reason why you would need to change that. It just felt wrong to hard-code the
diff --git a/lang/en/admin.php b/lang/en/admin.php
index cec064ff2453f..0b0617757306c 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -72,6 +72,9 @@
 $string['blockediplist'] = 'Blocked IP List';
 $string['blockinstances'] = 'Instances';
 $string['blockmultiple'] = 'Multiple';
+$string['blockprotect'] = 'Protect from delete';
+$string['blockprotect_help'] = 'The blocks instances will be protected from deletion from the site-wide context, and this is primarily used to protect the navigation and settings blocks which can be very hard to get back if accidentally delete.';
+$string['blockunprotect'] = 'Unprotect';
 $string['blocksettings'] = 'Manage blocks';
 $string['bloglevel'] = 'Blog visibility';
 $string['bloglevelupgrade'] = 'Blog visibility upgrade';
diff --git a/lib/blocklib.php b/lib/blocklib.php
index 4c816c2306868..d8a198732cb6d 100644
--- a/lib/blocklib.php
+++ b/lib/blocklib.php
@@ -997,9 +997,11 @@ public function edit_controls($block) {
         global $CFG;
 
         if (!isset($CFG->undeletableblocktypes) || (!is_array($CFG->undeletableblocktypes) && !is_string($CFG->undeletableblocktypes))) {
-            $CFG->undeletableblocktypes = array('navigation','settings');
+            $undeletableblocktypes = array('navigation','settings');
         } else if (is_string($CFG->undeletableblocktypes)) {
-            $CFG->undeletableblocktypes = explode(',', $CFG->undeletableblocktypes);
+            $undeletableblocktypes = explode(',', $CFG->undeletableblocktypes);
+        } else {
+            $undeletableblocktypes = $CFG->undeletableblocktypes;
         }
 
         $controls = array();
@@ -1037,7 +1039,9 @@ public function edit_controls($block) {
         }
 
         if ($this->page->user_can_edit_blocks() && $block->user_can_edit() && $block->user_can_addto($this->page)) {
-            if (!in_array($block->instance->blockname, $CFG->undeletableblocktypes)) {
+            if (!in_array($block->instance->blockname, $undeletableblocktypes)
+                    || !in_array($block->instance->pagetypepattern, array('*', 'site-index'))
+                    || $block->instance->parentcontextid != SITEID) {
                 // Delete icon.
                 $controls[] = array('url' => $actionurl . '&bui_deleteid=' . $block->instance->id,
                         'icon' => 't/delete', 'caption' => get_string('delete'));