I am not so sure about the unpaid dividends. Typically when corporate dividends are suspended, there is no obligation to ever pay them on a common share. The La Salle dividends are cumulative with that regard, because they were designed as a liquidation and preferred instrument.
I thought the 67 M debt was a TAC note, not an LSUK obligation. My problem with this info and article was the reserves on 839. They were quite large, and the last I had heard was that 839 was simply a managed runoff in a condition known as "reinsurance to close." There would be no reason for them to purchase that asset, since it was closed to new business. It is not a going concern, but is a reserve against formerly written business. A buyer could theoretically be interested in the income stream of well managed reserves, but they were already the manager and would collect the management revenue without purchasing the asset.
The articles and transactions you have described would make no sense under normal operating circumstances. It wouldn't surprise me if it was simply a theft of the reserves that they figure they can hide from us, and which the Trenwick and La Salle shareholders should have been entitled to. Any other purchase agreement would simply make no business sense. If the article is true, it is almost clear evidence of a crime.
It would be very interesting to watch those reserves, and any new writing against them.
The last scheme I read included Trenwick and TAC as equal partners in the 839 runoff and (I believe) also the 20% of 4444. I assumed that TAC was given the responsibility of paying both the LSRAF shareholder preferreds and the 67 M note from their half.