Good explanation P2C.
As a sharehoder too I am pleased to see the immediate share price effect but I'm a bit less sure about how this will position RR going forward. It does seem that, despite brave words about continuing their stand-alone smaller engine research programmes, they have finally conceded that the GTF is the way ahead i.e they have conceded the principal game-changing technology to PW: putting PW in the driving seat going forward and giving them the opportunity to call the shots. Clearly, RR still have the lead on large engines - the PW4000 being pretty much defunct - but, in future, if gears prove more effective than a third spool for larger engines too, this might also become PW's technological baby.