If any one is still interested in Contracts? I'll be brief. From information that is out, but unsubstantiated, the following is important to remember if engaged in a discussion of Commercial Contract.
A Contract really only requires three separate things to be valid, enforceable, and legal.
One, It must follow the Law, it may not contain elements that are illegal.
Two, At least two parties, who are competent.
Three, Consideration, generally money, but can be other benefit.
As re: RR and Qantas/Airbus, I'll repeat what I wrote earlier; given Joyce saying RR did not inform Qantas/Airbus of the "modification". This is important, and I'll explain why after.........
"A Party to a Contract, who acquires information that has a material bearing on the Contract, who then does not disclose this information to the other Party commits a Species of Fraud."
This is the linchpin of many lawsuits, civil and criminal. What it describes in legalese is what is known as a breach, (gap, or "break"). A Breach can be innocuous, or negligent, or willful, or fraudulent. It always puts the one in Breach at a profound disadvantage. At Breach, all language, and spirit, is suspended. Something that was contained in the language of the actual agreement can rear up and disallow the contract itself.
Any (and perhaps all) part of the contract is vulnerable, depending on how the Breach is to be healed, as both parties retain (hopefully) an interest in mitigating eachother's losses. In the case of the "Modification", each party will assess how important it was/is, and whether or not it was non-disclosed, and whether or not the non-disclosure (if it exists) affected the rights of the aggrieved Party. Any opinion on this matter is way premature, but I thought a basic positioning on the ball field is important.