if ( $file =~ /^London/ ) {
        $time_zone_func = gmtime;
        } else {
        $time_zone_func = localtime;
        }


  my $prev_days = $4 * 86400;
  if ( $prev_days ) {
  $TIMESTAMP = strftime($date_format, $time_zone_func(time - $prev_days));
  } else {
  $TIMESTAMP = strftime($date_format, $time_zone_func(time));
  }