Unless there is absolute proof that the fault could be traced back to the point of manufacture...

That's not the position - the relevant thing would be proof that the damage existed at the time of sale, regardless of how it had been caused (whether druring manufacture or poor storage, or damage in transit etc). Proof that it existed at point of manufacture would only be relevant if the claim was against the manufacturer.

The fact that an importer is not currently in business would not mean they did not carry liability for selling faulty goods, and I believe that if someone had purchased their business, that would make them, liable for such things. Rather like an unpaid debt turning up - which in effect is what this is.