With 'Retained rights' the idea is that you can prove partner's treaty rights up until the divorce and exercise of treaty rights by yourself from then on (more discussion on this thread:
http://www.immigrationboards.com/viewtopic.php?t=49031) but I'm no longer confident that this will avail you much if you are unable to provide evidence of your partner's treaty rights going right up to the time of the divorce.
I suspect your chances will hinge upon whether the UKBA would accept an application where the 5 year treaty rights period ended some time ago. Do you have evidence of treaty rights covering a 5 year period sometime between 2006 and now? This would be your minimum for an EEA4 to have a chance of success. If you have that, it could be argued that if you acquired PR in 2011, only a 2 year UK absence would then break that, and therefore you could apply successfully now, demonstrating that you are currently in the country and providing the evidence for that 5 year period. What I'm unsure about, though, is how the UKBA would view an EEA4 application based on a 5 year period that ended some time ago.
Do any experts have further advice on this scenario?