OP, I've summarised what I understand from your post below. Can you provide answers to the question marks? And also correct anything which I may have misunderstood.
Workpermit EC date: 23.01.2008
Date of first entry on WP: 26.04.2008
WP Expiry date: 31.12.2009
Tier2 ICT in-country LTR expiry date: 11.12.2012
Left UK on 22-Aug-2010
Tier2 ICT LTR terminated on:
?? (Do you know when this was done? I'm making a guess that your T2-ICT employer would have submitted a NPEE to the UKBA to end your LTR grant when you resigned. Making a SAR may help find out this date, if you don't know it.)
Tier2 General EC application date:
??
Tier2 General EC date: 30.11.2010
Tier2 General Expiry date: 08.12.2012
Date of First entry to UK on T2G: 22.12.2010
Tier1 General LTR application date:
??
Tier1 General LTR effective date: 03.05.2011
Tier1 General LTR expiry date: 03.05.2013
While not exactly the same, you may find it useful to read the following topic, which is similar:
http://www.immigrationboards.com/viewtopic.php?p=779830