Da4orce you beat me to it. The duct that was replaced was the root cause of the incident with XV227, and an analysis was carried out by BAE Systems into the SCP duct and others in the system and hence the recommended lifing policy that will be/has been introduced to the MR2, as Da4orce said if you wish to know more ask the RAF/MOD/BAE Systems.
25 years history is hardly irrelevant, especially if you are able to trawl the archived maintenance documentation/supply documentation/use the IPT/DA to do a check against the part number of a component and find how many of those components have been replaced and why, this is done in every maintenance/first line environment when something is found that appears out of the 'norm' or post a ground/air incident. Additionally why are you bringing MRA4 into the discussion it is not relevant, the analysis referred to has been carried out on MR2 post XV227 not on MRA4, as you rightly pointed out it is has different systems/engines/layout to the MR2.
Throughout this thread most of the people are advising waiting for the outcome of the BOI, but TD/Da4orce and others have a right to ask technical questions so they can understand what could of gone wrong, to help them ask the right questions under the FOI/understand those responses, to help get closure for their loss and prepare them better to understand the technical content of the BOI when it is released.