WW has always said Brexit will have limited effect on IAG. He's never (as far as I am aware) specifically said how he thinks it will alter BA's bottom line, but BA currently provides the vast majority of IAG's profits, so he either expects this to continue or that the other airlines within the group will take over. There are many who believe Brexit will result in a huge hit to BA's premium customer base, but that all depends on what Brexit actually means. Personally, I think the negotiations will continue for such a lengthy period of time with no real direction, that people will just get bored of it all and businesses will either bumble along without any innovative plans for the future, or they will leave the UK and get on with growing.