Mrs Henderson was presented with WALGA's highest individual honour on August 7 for her outstanding service to the Subiaco community and local government.
"I am really quite humbled by it, because they don't give it lightly," she said.
"Surrounding myself with really wonderful people, both in terms of the elected members and administration I have been privileged to work with, that is the way to achieve great things."
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READ NOWWALGA president Lynne Craigie said Mrs Henderson was renowned for her tireless commitment to improving equity and access in the community.
City of Subiaco councillors Judith Gedero and Murray Rowe received WALGA merit awards for their distinguished service.
Cr Gedero said she had loved every moment of her 12 years on council.
"Every meeting stands out in my memory and I am always pleased when I can do something for the people," she said.
Cr Rowe said that although the award was a good opportunity to reflect on his decade-long journey as a councillor, there were still a lot of challenges ahead. "I would like to see us lead from the front and do more for business in Subiaco," he said.