Henderson is a former vice-principal and principal of Mount Temple Comprehensive School in Dublin. In 2006 she was an educational consultant.
Henderson has been involved with Guiding since childhood. As an adult, she has held numerous positions at both national and international level.
Henderson has been President of The Irish Girl Guides. She has also been an International Commissioner for the same. She was Chair of the Conference Planning Team for the 30th World Conference held in Dublin in 1999.
Henderson was Chairman of the Europe Region of WAGGGS from 1989 - 1999. She was awarded the WAGGGS Bronze medal in 1999. She was elected to the World Board in 2002 and in 2005 became the World Board Chairman.
- "Chairman's Message - February 2006". World Association of Girl Guides and Girl Scouts. February 2006. http://www.wagggsworld.org/en/about/Chairmansmessage/messageFebruary2006. Retrieved 2006-10-07.
- "nyci newsletter: Member Organisations News Archive". National Youth Council of Ireland. March 1998. http://www.youth.ie/news/arc_art.php?id=226. Retrieved 2006-10-07.
- "nyci newsletter: Member Organisations News Archive". National Youth Council of Ireland. July 2002. http://www.youth.ie/news/arc_art.php?id=655. Retrieved 2006-10-07.
- "WAGGGS World Conference 2005". Cathoic Guides of Ireland. http://www.girlguidesireland.ie/worldconf.shtml. Retrieved 2006-10-07.