So I looked up the meanings of the word "former" and the descriptions were as follows :
- Having previously been a particular thing.
- Denoting the first or first mentioned of two people or things.
I dont know whether having and denoting are gerunds or participles and although I can normally tell the difference sometimes its very difficult.
Examples of where its clear which one it is :
Gerund : Walking on the beach is fun.
Participle : Walking on the beach, I got sunburned because I forgot to use sunscreen.