I am 22 (was 21 when applied for my insurance) have lost my license for speeding and have two red light offences (I'm not as irresposible as that makes me sound by the way) To insurance companies, short of adding a DUI to that I don't see how it comes much worse. After trying pretty much all the insurance companies, who wouldn't touch me with my 71 big block. I finally rang Shannons and asked to speak to one of the managers straight away. I explained my situation and my passion for my car etc etc, had a very pleasant and productive conversation and ended up getting comprehensive at agreed value for about $1400 per annum (although it would have been less without the offences). The only other people who even came close was NRMA classic and they wanted about $5500.
And Shannons didn't even ask wheather it was left hand drive or not.
In all my experiences.... and I tried hard for a while, it would seem that weather someone gives you insurance or not is up to the real persons descision on the other end of the line. If you make yourself known to the right person, are able to build some sort of rapport with the guy you will be fine. If you don't have much luck, try sending a polite and intelligent letter to the right person.
When you first ring up a company the first guy you get is always not all that informed, and when he hears the words DUI or anything that portains to "yound and stupid" the alarms go off in their head and will always err on the side of caution.
You could also try actually visiting a branch and asking to speak to a manager in person. Bringing the more human element to the interaction is also much more likely to yeild results, providing you don't come off as a d*ck head that is, or like someone who they don't want to insure.
Anyone can get insurance, but sometimes it comes at an unavoidable cost.