Final Solution was the removal of a tab character after the "=" sign on line 23 in modules/repgen/hooks.php.
Any function that starts with an underscore should not have any preceding tabs in the current version of PHP (at least the one on Debian Squeeze) if immediately on the RHS of an assignment statement.
The PHP version tested was:
# php -version
PHP 5.3.3-7+squeeze14 with Suhosin-Patch (cli) (built: Aug 6 2012 20:08:59)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
There are 83 files in the standard FA distribution having a tab preceding a gettext function - _("xxx") - usage and this has never been a problem. Only in this case it was an assignment to a variable (an array variable in this instance).
The attached patch addresses a similar "=\t" issue with modules/repgen/repgen_strings.php as well.
Bugs yet to be fixed:
On activating the Reports Generator extension, when we try to edit, delete or copy the first and only report in the default list, we get to see the report iself like pressing the Run button. The Edit, Copy and Delete functionality seems lost.