As I understand it, BWA's sole assets were a couple of (one would assume) fully depreciated BAC1-11s and a load of BAC1-11 spares and tooling. I have been informed - and I'm not sure how reliably, so make of it what you will - that the spares and tooling for the other aircraft were leased or alternatively owned by WAS.
Is WAS a 100% owned subsidiary of BWA plc - and if so, what are its declared assets? Who is in the picture to buy it as a going concern - and do they have any links to the new company that has been discussed?
This situation sounds very much like that of Gill Airways, where banks provided funds against cashflow - effectively on an unsecured basis.
If HSBC was aware that BWA had lost its two European contracts (with substantial amounts owing); and that the West African flights were having to use OM's aircraft because the 757 had insufficient baggage capacity, then it is obvious that the cashflow against which the bank was relying for its debt service had, to a very large extent, disappeared. Under those circumstances it is not unreasonable for them to pull the plug.
As to whether or not anything improper happened - well, it depends on what contracts have ended up with the new company. Certainly, those that were lost - and left BWA with bad debts - were not taken over; though it would be interesting to see if any commitments for next summer that should have gone to BWA (and perhaps convinced HSBC that there was light at the end of the tunnel) have been diverted to the new company.