Crystal ball gazing: my view is that we will see an overall drop in demand for flight to and from the UK. Unless flight connections somehow becomes much more complicated for EU nationals (unlikely given how onerous the current arrangements are for everyone, including British citizens) long-haul demand from Europe is unlikely to change much in the short term.

So I expect the savings to diminish, caused by a weaker currency over the next three to five years (i.e., until we get through the next cyclical recession and either have a trade deal in place or the markets - not just currency markets but importers and exporters - have priced in the lack of one, after which normal factors come into play) as well as a lack of demand, pushing down ex-UK fares in sterling.

Long term? It depends how BA reacts to the position. At the moment, W cabins are too small but BA is OK with letting J cabins soak up the excess so that it has the capacity to offer expensive J tickets when needed.

It could respond to reduced demand by cutting prices and filling planes to keep slots, in which case ex-EU prices would probably be similar in pounds, and ex-UK prices less in sterling. Equally it could find that revenue is maximized by leaving things as they are or even simply selling fewer, but more expensive J tickets and keeping W and Y prices correspondingly high.

Over a slightly longer period, it could also move away from First and expand WTP, with a smaller J cabin and a better WTP product (e.g., the new CX and AA PE products with seats with extra leg support, maybe moving to something close to angle flat throughout). This would be particularly so if more travel policies move away from J altogether and make W the highest permitted long-haul cabin. Eventually this would allow BA to charge correspondingly high prices for those who still need or are allowed J travel.

Finally, it could simply cut back on flights and slots, and opt not to replace planes as they leave the fleet, charging the same or more for fewer tickets. The only problem there is that those slots, once given back, would be difficult to retrieve, but if Brexit represents a long-term shift in capacity of the British economy as a whole, this may still be the right strategy.