I'm still in part 2, and it's clear that the mess wasn't just the direct result of trying (and failing) to wriggle out of living up to guarantees promised decades earlier. Marketing decisions throughout the 80s and 90s were placed ahead of being sure they'd be able to continue stated policies. The guaranteed rates were just one of these.
So, for example, they paid some investors more than they 'deserved' in order to attract many more new investors through appearing to be towards the top of the various performance league tables. You can't do this forever.
The phrase 'pyramid scheme' is coming to mind. In one very important sense, it's not as bad as a classic pyramid con - they didn't pocket the money (although they paid themselves nicely). But as these are the people expected to perform over thirty plus years to provide a pension for their investors, it doesn't inspire confidence.
I wonder what a similar enquiry at other 'life offices' would turn up.