diff --git a/Classes/PHPExcel/Reader/Excel2007.php b/Classes/PHPExcel/Reader/Excel2007.php
index d197eff..7ae0a99 100644
--- a/Classes/PHPExcel/Reader/Excel2007.php
+++ b/Classes/PHPExcel/Reader/Excel2007.php
@@ -262,36 +262,34 @@ class PHPExcel_Reader_Excel2007 extends PHPExcel_Reader_Abstract implements PHPE
 
 
 	private function _castToFormula($c,$r,&$cellDataType,&$value,&$calculatedValue,&$sharedFormulas,$castBaseType) {
-//		echo 'Formula<br />';
-//		echo '$c->f is '.$c->f.'<br />';
+//		echo 'Formula',PHP_EOL;
+//		echo '$c->f is '.$c->f.PHP_EOL;
 		$cellDataType 		= 'f';
 		$value 				= "={$c->f}";
 		$calculatedValue 	= self::$castBaseType($c);
 
 		// Shared formula?
 		if (isset($c->f['t']) && strtolower((string)$c->f['t']) == 'shared') {
-//			echo 'SHARED FORMULA<br />';
+//			echo 'SHARED FORMULA'.PHP_EOL;
 			$instance = (string)$c->f['si'];
 
-//			echo 'Instance ID = '.$instance.'<br />';
+//			echo 'Instance ID = '.$instance.PHP_EOL;
 //
-//			echo 'Shared Formula Array:<pre>';
+//			echo 'Shared Formula Array:'.PHP_EOL;
 //			print_r($sharedFormulas);
-//			echo '</pre>';
 			if (!isset($sharedFormulas[(string)$c->f['si']])) {
-//				echo 'SETTING NEW SHARED FORMULA<br />';
-//				echo 'Master is '.$r.'<br />';
-//				echo 'Formula is '.$value.'<br />';
+//				echo 'SETTING NEW SHARED FORMULA'.PHP_EOL;
+//				echo 'Master is '.$r.PHP_EOL;
+//				echo 'Formula is '.$value.PHP_EOL;
 				$sharedFormulas[$instance] = array(	'master' => $r,
 													'formula' => $value
 												  );
-//				echo 'New Shared Formula Array:<pre>';
+//				echo 'New Shared Formula Array:'.PHP_EOL;
 //				print_r($sharedFormulas);
-//				echo '</pre>';
 			} else {
-//				echo 'GETTING SHARED FORMULA<br />';
-//				echo 'Master is '.$sharedFormulas[$instance]['master'].'<br />';
-//				echo 'Formula is '.$sharedFormulas[$instance]['formula'].'<br />';
+//				echo 'GETTING SHARED FORMULA'.PHP_EOL;
+//				echo 'Master is '.$sharedFormulas[$instance]['master'].PHP_EOL;
+//				echo 'Formula is '.$sharedFormulas[$instance]['formula'].PHP_EOL;
 				$master = PHPExcel_Cell::coordinateFromString($sharedFormulas[$instance]['master']);
 				$current = PHPExcel_Cell::coordinateFromString($r);
 
@@ -304,7 +302,7 @@ class PHPExcel_Reader_Excel2007 extends PHPExcel_Reader_Abstract implements PHPE
 																			$difference[0],
 																			$difference[1]
 																		 );
-//				echo 'Adjusted Formula is '.$value.'<br />';
+//				echo 'Adjusted Formula is '.$value.PHP_EOL;
 			}
 		}
 	}
diff --git a/Classes/PHPExcel/ReferenceHelper.php b/Classes/PHPExcel/ReferenceHelper.php
index f7d1370..ff3ed2c 100644
--- a/Classes/PHPExcel/ReferenceHelper.php
+++ b/Classes/PHPExcel/ReferenceHelper.php
@@ -702,7 +702,7 @@ class PHPExcel_ReferenceHelper
 								$cellIndex = $column.$row;
 
 								$newCellTokens[$cellIndex] = preg_quote($toString);
-								$cellTokens[$cellIndex] = '/(?<![A-Z])'.preg_quote($fromString).'(?![A-Z])/i';
+								$cellTokens[$cellIndex] = '/(?<![A-Z\$\!])'.preg_quote($fromString).'(?![A-Z])/i';
 								++$adjustCount;
 							}
 						}
@@ -728,7 +728,7 @@ class PHPExcel_ReferenceHelper
 								$cellIndex = $column.$row;
 
 								$newCellTokens[$cellIndex] = preg_quote($toString);
-								$cellTokens[$cellIndex] = '/(?<![A-Z])'.preg_quote($fromString).'(?!\d)/i';
+								$cellTokens[$cellIndex] = '/(?<![A-Z]\$\!)'.preg_quote($fromString).'(?!\d)/i';
 								++$adjustCount;
 							}
 						}
@@ -740,8 +740,8 @@ class PHPExcel_ReferenceHelper
 					foreach($matches as $match) {
 						$fromString = ($match[2] > '') ? $match[2].'!' : '';
 						$fromString .= $match[3];
-						$modified3 = $this->updateCellReference($match[3],$pBefore,$pNumCols,$pNumRows);
 
+						$modified3 = $this->updateCellReference($match[3],$pBefore,$pNumCols,$pNumRows);
 						if ($match[3] !== $modified3) {
 							if (($match[2] == '') || (trim($match[2],"'") == $sheetName)) {
 								$toString = ($match[2] > '') ? $match[2].'!' : '';
@@ -753,7 +753,7 @@ class PHPExcel_ReferenceHelper
 								$cellIndex = $column.$row;
 
 								$newCellTokens[$cellIndex] = preg_quote($toString);
-								$cellTokens[$cellIndex] = '/(?<![A-Z])'.preg_quote($fromString).'(?!\d)/i';
+								$cellTokens[$cellIndex] = '/(?<![A-Z\$\!])'.preg_quote($fromString).'(?!\d)/i';
 								++$adjustCount;
 							}
 						}
@@ -890,7 +890,6 @@ class PHPExcel_ReferenceHelper
 			// Verify which parts should be updated
 			$updateColumn = (($newColumn{0} != '$') && ($beforeColumn{0} != '$') &&
 							 PHPExcel_Cell::columnIndexFromString($newColumn) >= PHPExcel_Cell::columnIndexFromString($beforeColumn));
-
 			$updateRow = (($newRow{0} != '$') && ($beforeRow{0} != '$') &&
 						  $newRow >= $beforeRow);
 
diff --git a/changelog.txt b/changelog.txt
index 17242b7..8587495 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -29,6 +29,8 @@ Fixed in develop branch for release v1.8.0:
 - Bugfix:   (MBaker)                        - Style error with merged cells in PDF Writer
 - Bugfix:   (MBaker)                        - Problem with cloning worksheets
 - Bugfix:   (tavoarcila)  Work Item GH-259  - Bug fix reading Open Office files
+- Bugfix:   (MBaker)      Work item 20397   - Serious bug in absolute cell reference used in shared formula
+                                              Would also have affected insert/delete column/row
 - Feature:  (amerov)                        - Implementation of the Excel HLOOKUP() function
 - Feature:  (MBaker)                        - Added "Quote Prefix" to style settings (Excel2007 Reader and Writer only)
 - Feature:  (MBaker)                        - Added Horizontal FILL alignment for Excel5 and Excel2007 Readers/Writers, and Horizontal DISTRIBUTED alignment for Excel2007 Reader/Writer