Originally Posted by
heckenhocker
hmm, so at 10% fare, it's cheaper (at least in Y, Y+) to take an infant + its hold bag + carryon bag than to pay the "extra bags" fee at £30 per bag to US. Do you actually have to bring the infant...can a teddybear travel

Not quite. LHR-JFK in WT for example is £130 or so return for infant.