Leon,
Methinks SWO needs to do his homework, the Royal Warrant clearly states the ACSM is after medals for Meritorious Service, on checking Meritorious service . What serves to confuse is the ACSM has the word "Campaign" in its title when it is in fact awarded for long service thereby explaining its juniority. Therefore, the correct order (assuming entitled) would be: Honours & Awards - Campaign Medals (in order of award to the individual) - QGJM - QDJM - MSM - ACSM94 - ACSM11 - LSGC - Foreign Awards.
There are funnies, Op Agila being one, it sits at the most junior but above LSGC regardless of when awarded. I recall this is because it was never recognised as a campaign medal but a peacekeeping medal.
Simples.