I had my badge refused due to a caution which happened about 4 years before applying to the sia , I did tell them in my application because i didn't know if it showed up on the checks. Anyway i appealed and did win, I wrote a letter myself explaining the caution and about how i had change my life for the better after 1 silly mistake and my boss also wrote me letter too. Best way is to be up front about it all and come clean with your boss, Not sure if it would be worth appealing tho as your last was only 2007!