What if my ex failed to declare a pension?

Hi

I am looking for guidance since my appears to have failed to declare one of her pensions which may have been quite a significant part of the pot. We were divorced in Aug 2011 but I have just found discussions of a case in 2015 where the financial settlement could be re-visited if things had not been fully declared.

How do I go about finding the CETV of the company pension at the time of our divorce and what are the chances of getting settlement reviewed.

How much are you likely to be talking?

Would it have completely changed the outcome if it had been included?

Was your financial settlement by consent through discussion, by mediation or done on a form E?

Hi
Well I don't know the full value. But I doubt that her solicitors would have overlooked it if it was insignificant. All I know is that it was from a large pharmaceutical and she was talking the other week about taking early retirement possibly. How can I estimate its value or do I have to ask her to obtain a CETV for the date of the divorce?
The paperwork from her solicitors was only given to me three days before the final court hearing. I was self-representing and only just coming out of depression so I assumed everything was above board.