For your outbound trip (PER-SIN-LHR // LHR-CAI), I would imagine it would be:
- For PER-SIN-LHR, all on QF, you get your allowance as per being a QF WP, which is 96 kg (or more accurately, 3 x 32 kg bags).
- For LHR-CAI, on BA, you get the allowance afforded to you as a BA Euro Traveller / World Traveller, which is 1 x 23 kg bag.
This is my guess; the outbound to LHR is obvious, but I suspect that LHR-CAI will not be covered under your nominal QF allowance because:
- You can't check through your bags from PER all the way to CAI (36 hours stopover - no one will do that).
- Your LHR-CAI flight is probably on a separate flight segment / journey, which means the baggage allowances are evaluated all over again. (It would be unlikely that you can have a 36 hour stopover where all of those flights from PER to CAI can be covered under a single, marketable flight segment).
As for your return, CAI-LHR-SIN-PER, I'd presume that this entire mess is on one flight segment (quite possible, since the QF booking engine should conceivably send you back to LON to make sure you can connect on any possible flight going back to PER).
The naive guess for your return is that BA (or the already foreshadowing incompetent contracted agent they use at CAI) will force you to stick to the BA allowance of 1 x 23 kg bag. However, if you are checking all the way to PER (i.e. one flight segment and this is possible), then the IATA rules actually state that the allowance of the MSC will apply, which in this case is QF. (Since this flight crosses IATA sub-areas, the first carrier to exit a sub-area is the MSC; in this case, QF is the first carrier to exit the Euro/ME/Africa sub-area, whereas BA only flies
within a sub-area).
With your QF baggage allowance, it will naturally be 96 kg (or 3 x 32 kg) going home.
Problem is if the agents at CAI don't believe you and won't process you through. Unless you print out the relevant IATA Resolution for this procedure, along with the QF allowances, then you might have some hope. I have my healthy level of doubts, however, whether the BA agents in CAI (which I will guess to be contracted and not BA employed) will actually be competent enough to realise all of this (if they are even competent to do their jobs at all, period, and that is
if they don't need to be bribed in the first place).