How to customise Webform results table
OK, so I solved it myself.

Open and edit the webform.submissions.inc file in the includes folder of the module

In the Return all the submissions for a particular node. section find the code with the comment "// Join to the users table to include user name in results."

 // Join to the users table to include user name in results.
  $pager_query-&gt;leftJoin('users', 'u', 'u.uid = ws.uid');
  $pager_query-&gt;fields('u', array('name'));
  if (isset($filters['u.uid']) &amp;&amp; $filters['u.uid'] === 0) {
    if (!empty($_SESSION['webform_submission'])) {
      $anonymous_sids = array_keys($_SESSION['webform_submission']);
      $pager_query-&gt;condition('sid', $anonymous_sids, 'IN');
    }
    else {
      $pager_query-&gt;condition('sid', 0);
    }
  }


To add my country section I had to find the table in phpMyAdmin that contained my taxonomy data. In this case it was "field_data_field_counrty" (I've spelled country wrong i know but I couldn't change it after).

From that I figured out that the entity ID was the the user ID in the Users table. This is because I had used the country taxonomy on the registration form. 

The syntax for the inner join query is 'Table, Table Alias, Condition, Arguments'.
From that my innerjoin became,

 $pager_query-&gt;innerJoin('field_data_field_counrty ', 'fld_Country', 'fld_Country.entity_id = ws.uid' );


The field syntax is 'Table Alias, Field Name', so my field selection became,

$pager_query-&gt;fields('fld_Country', array('field_counrty_tid'));


This gave me the country ID number that had been assigned to the taxonomy term. I then had to cross reference that field with the taxonomy data table to retrieve the name of the country the ID referred to. That was done with another innerjoin.

$pager_query-&gt;innerJoin('taxonomy_term_data ', 'taxonomy_Country', 'taxonomy_Country.tid = fld_Country.field_counrty_tid' );


This time the field I needed to retrieve was called name. However, 'name' had already been used further up in the original code for the user name. So to add an alias to the field I had to use addField instead of fields. The syntax for addField is 'Table Alias, Field, Alias'. My code became,

 $pager_query-&gt;addField('taxonomy_Country', 'name', 'tax_name');


The code as a whole is:

 // Join to the field country table to include Country ID in results.
  $pager_query-&gt;innerJoin('field_data_field_counrty ', 'fld_Country', 'fld_Country.entity_id = ws.uid' );
  $pager_query-&gt;fields('fld_Country', array('field_counrty_tid'));
  $pager_query-&gt;innerJoin('taxonomy_term_data ', 'taxonomy_Country', 'taxonomy_Country.tid = fld_Country.field_counrty_tid' );
  $pager_query-&gt;addField('taxonomy_Country', 'name', 'tax_name');


Further down in the code is the section:

 $result = $pager_query-&gt;execute();

  $sids = array();
  foreach ($result as $row) {
    $sids[] = $row-&gt;sid;
    $submissions[$row-&gt;sid] = new stdClass();
    $submissions[$row-&gt;sid]-&gt;sid = $row-&gt;sid;
    $submissions[$row-&gt;sid]-&gt;nid = $row-&gt;nid;
    $submissions[$row-&gt;sid]-&gt;serial = $row-&gt;serial;
    $submissions[$row-&gt;sid]-&gt;submitted = $row-&gt;submitted;
    $submissions[$row-&gt;sid]-&gt;remote_addr = $row-&gt;remote_addr;
    $submissions[$row-&gt;sid]-&gt;uid = $row-&gt;uid;
    $submissions[$row-&gt;sid]-&gt;name = $row-&gt;name;
    $submissions[$row-&gt;sid]-&gt;is_draft = $row-&gt;is_draft;
    $submissions[$row-&gt;sid]-&gt;preview = FALSE;
    $submissions[$row-&gt;sid]-&gt;data = array();


In this section I added the line:

        $submissions[$row-&gt;sid]-&gt;CountryID = $row-&gt;tax_name;


To display the data, we now need to edit the webform.report.inc file. Find the section near the top that says,

 foreach ($submissions as $sid =&gt; $submission) {
    $row = array(
      $submission-&gt;is_draft ? t('@serial (draft)', array('@serial' =&gt; $submission-&gt;serial)) : $submission-&gt;serial,
      format_date($submission-&gt;submitted, 'short'),

    );
    if (webform_results_access($node, $user)) {
      $row[] = theme('username', array('account' =&gt; $submission));
      $row[] = $submission-&gt;remote_addr;


I then added the following line after the format_date section to add my new column after the submitted column.

      $submission-&gt;CountryID,


To  add the header for the new column find the section with the comment,

 * Theme the header of the submissions table.


I then added the following line after the submitted section,

    array('data' =&gt; t('Country'), 'field' =&gt; 'tax_name'),


Save both files and view a webform results page (providing it has a submission).
Your new column should now display.

I hope this helps anyone else that is confused on this subject!

Happy new year everyone!!!