Nige,
The Board DID make reference to a fuel tank fire suppression system but concluded that this would not have saved the aircraft. They also believe that if the risk assessment of the No. 7 tank dry bay had been conducted accurately, that measured may have been taken to reduce the severity of a fire in this zone.
I was very cynical prior to the BoI release, but I believe (having read the entire report) that the report is as thorough as possible within their TORs.
Had a fire warning and suppression system been fitted in the dry tank bay, with the inclusion of fire retardant paint, the crew MAY have had precious minutes to reach Kandahar.