On BREXIT ...
As Britain is not a signatory to the Schengen Agreement there should be no requirement for physical changes to the immigration infrastructure at UK airports. We have passport checks and customs in place and correctly channeled already.
I would not expect BREXIT to result in any significant change in levels of demand for air travel. For one thing, Britain is likely to remain inside the Single European Market. I don't sense any measurable public objection to this ... the 'Common Market' (as opposed to Federal Europe governed from Brussels and financed by the Euro) is what we signed up for originally. And, despite pre-ballot rhetoric, the Single Market suits both sides very well. Euroland exports far more to us than we do to them. They would be foolish to jeopardise tariff-free access to 'Treasure Island' (as we are known). One positive is that Britain would be free to rebuild trade relations with partners outside the EU, including former Commonwealth countries. This would be good news for air travel demand.
I do not consider BREXIT a threat to MAN's operation at any level.