Thanks for picking up on this.
As far as I can tell, there is no Shareholders Agreement. I only have a copy of the Articles of Association and understand a Shareholders Agreement is no legal requirement. I don't remember ever seeing or signing one myself either and given our/their style of business, I'd be surprised if there was one. So no SA.
The rest is to my most recent knowledge at the start of financial year 2013-14 when I was still involved. Perhaps it has changed but until the new annual reports are in, I have no way of knowing.
No debts to speak of. It's 'just' a medical distribution company so in terms of assets, no great deal involved like significant IP, no property or machinery owned etc. A database of customers, a reputation etc. sure, as well as some small NHS tenders won (no firm commitments from the NHS part though to actually buy). So no significant assets to speak of.
Cash flow does play a role as they offered me instalments of about 2K a month up to the total they had offered.
They've not made clear whether it's the company offering to buy back the shares in a company buy-back deal or (one of) the individual directors seeking to have the shares transferred. I understand there is a slight difference procedurally and perhaps tax-implications, capital gains tax etc. I don't know whether this has any bearing on my potential strategies.
The irony in all this is, if the value really has tanked 90% just because I left, it shows they value me at 90% of the total company value! They should have thought of that earlier then... But yes, I was valuable or even instrumental given their notable absence but that doesn't change the fact the company makes a certain level of turnover and resulting profits which continued (i've seen it) after I resigned. And they are responsible for keeping up the performance, not me.
I'll check the Company Act references you've kindly given. If you have any further thoughts based on the above, or additional questions, I'm all ears.