I can see a similar price, essentially £200 per adult in Carrier Surcharges at the moment. The previous £140 seems low, if it was purchased as a single fare for 2 adult + 1 infant. The infantt surcharge is £16 so Iit won't have been that. The only thing I can think of is that BA relaxed its fare policies on single fares, normally they are more expensive than return fares over the Atlantic, and to make the numbers work they may have squeezed down the carrier surcharge to get the fare to a lower level. But even then £140 would have been a very low rate for that route, if bought as a single from USA to UK.