on the webassist/plugins/registration/full/registration.php page, change line 377;
<option value="<?php echo $row_Countries['CountryISO']?>"<?php if (!(strcmp($row_Countries['CountryISO'], isset($wa_settings['Country'])?$wa_settings['Country']['value']:'US'))) {echo "selected=\"selected\"";} ?>><?php echo $row_Countries['CountryName']?></option>
to:
<option value="<?php echo $row_Countries['CountryISO']?>"<?php if (!(strcmp($row_Countries['CountryISO'], isset($wa_settings['Country'])?$wa_settings['Country']['value']:'GB'))) {echo "selected=\"selected\"";} ?>><?php echo $row_Countries['CountryName']?></option>