I have trawled through the posts and comments and while there are lots of useful info none that I can find to help with my particular issue.
The problem I have is trying to track how long a ticket spends within a particular group. If a new ticket spends 3 days with a Tier 1 support group and is then escalated to a Tier 2 support group the ticket appears to be 3 days old and there is no way to identify whether Tier 2 have only just received the ticket or have received the ticket 3 days ago.