Exactly where does a mutable blockchain fit in the financial ecosystem?

I'm intrigued to see the use case, due to be announced by Accenture tomorrow, that would mean that a mutable 'Blockchain' within a private permissioned system is anything but.

Of course, I could be wrong - but this does seem a strange interpretation of Blockchain as used for financial institutions. Part of the beauty is being able to track back through transaction history to see what actually happened. See - I'm not saying that fat-finger trading doesn't happen - but by admitting it does happen and recording the reversal in a later block you end up with more transparency in the process.

Source: http://www.ft.com/cms/s/0/f5cd6754-7e83-11e6-8e50-8ec15fb462f4.html?siteedition=uk#axzz4KjPI905k