diff --git a/git_filter_branch_fix_author.sh b/git_filter_branch_fix_author.sh
new file mode 100755
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+++ b/git_filter_branch_fix_author.sh
@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+#  vim:ts=4:sts=4:sw=4:et
+#
+#  Author: Hari Sekhon
+#  Date: 2020-12-04 17:46:52 +0000 (Fri, 04 Dec 2020)
+#
+#  https://github.com/HariSekhon/bash-tools
+#
+#  License: see accompanying Hari Sekhon LICENSE file
+#
+#  If you're using my code you're welcome to connect with me on LinkedIn and optionally send me feedback to help steer this or other code I publish
+#
+#  https://www.linkedin.com/in/HariSekhon
+#
+
+set -euo pipefail
+[ -n "${DEBUG:-}" ] && set -x
+srcdir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# shellcheck disable=SC1090
+. "$srcdir/lib/utils.sh"
+
+# shellcheck disable=SC2034,SC2154
+usage_description="
+Rewrites the current Git branch using git filter-branch to change the Author/Committer name and/or email address
+
+For each commit in the current branch history, if both:
+
+	- the Author or Committer Name matches the <old_name>
+    - the Author or Committer Email matches the <old_email>
+
+then both the Author and Committer names and emails are set to <new_name> and <new_email>
+
+
+Must be called from the top level directory of the repository
+
+You may still see the old name/email in the local repo's git log, test by cloning to a new repo and if happy then park the old checkout and checkout clean
+
+
+DANGER: this rewrites Git history.
+        Do not use this carelessly as it rewrites Git history.
+        Always have a backup.
+        Do not do this on pushed branches unless you are an Expert and intend to
+
+If there is already a git filter-branch rewrite backup in .git/refs/original, git filter-branch will refused to proceed - specify \$FORCE_GIT_REWRITE=1 in the environment to force the rewrite
+"
+
+# used by usage() in lib/utils.sh
+# shellcheck disable=SC2034
+usage_args="<old_email> <new_email> [<new_name>]"
+
+help_usage "$@"
+
+min_args 2 "$@"
+
+old_email="$1"
+new_email="$2"
+new_name="${3:-}"
+
+opts=""
+if [ -n "${FORCE_GIT_REWRITE:-}" ]; then
+    opts="-f"
+fi
+
+for x in "$old_email" "$new_email"; do
+    # email_regex is defined in lib/utils.sh
+    # shellcheck disable=SC2154
+    # <Hari Sekhon@TeamCity> doesn't match - technically this may not match real emails so be a bit more lax
+    #if ! [[ "$x" =~ $email_regex ]]; then
+    if ! [[ "$x" =~ @ ]]; then
+        die "Invalid email '$x' given"
+    fi
+done
+
+echo
+echo "DANGER!!!"
+echo
+echo -n "You are about to replace all Author and Committer references from '$old_email' to '$new_email'"
+if [ -n "$new_name" ]; then
+    echo " and change the name field to '$new_name'"
+fi
+echo
+read -r -p "DANGER: are you absolutely sure? (y/N)  " answer
+echo
+
+shopt -s nocasematch
+if ! [[ "$answer" =~ ^(y|yes)$ ]]; then
+    echo "Aborting..."
+    exit 1
+fi
+shopt -u nocasematch
+
+timestamp "Starting git filter-branch replacement"
+echo
+
+git filter-branch "${opts[@]}" --tag-name-filter cat --env-filter \
+    "
+    if [ \"\$GIT_AUTHOR_EMAIL\"    = '$old_email' ] ||
+       [ \"\$GIT_COMMITTER_EMAIL\" = '$old_email' ]; then
+        if [ -n '$new_name' ]; then
+            export GIT_AUTHOR_NAME='$new_name'
+            export GIT_COMMITTER_NAME='$new_name'
+        fi
+        export GIT_AUTHOR_EMAIL='$new_email'
+        export GIT_COMMITTER_EMAIL='$new_email'
+    fi
+    " \
+    -- --all