You are mostly refuting proposals that nobody made.
Nobody suggested that Britain could unilaterally announce Schengen membership, confiscate the Channel Tunnel or selectively ban Air France while preserving identical British Airways flights.
The proposition was explicitly hypothetical and multilateral: if Britain and the relevant European states accepted that aviation demand had to be reduced because of binding climate limits, what legal and economic arrangements could replace short-haul flights?
Yes, joining Schengen would require unanimous consent. That makes it a major diplomatic undertaking. It does not make the proposition logically or legally impossible.
“Political appetite is exactly zero” is simply your prediction that politics can never change.
The claim that EU airlines possess an absolute right to operate every route is also wrong. EU Regulation 1008/2008 specifically allows traffic rights to be restricted for serious environmental reasons, subject to proportionality, non-discrimination and Commission oversight.
France has already used that mechanism. The UK-EU TCA likewise permits non-discriminatory environmental restrictions.
A negotiated reciprocal withdrawal of London–Paris, London–Brussels and London–Amsterdam flights would therefore be very different from Britain arbitrarily excluding foreign airlines. It would require treaty-level agreement and would apply to all operators.
Nor would changing the tunnel’s economics constitute “state theft”. Getlink operates under a concession granted by the British and French governments. Those governments cannot tear it up without consequences, but they can negotiate amended charges, purchase capacity, subsidise access, extend or alter the concession in exchange for consideration, or compensate the company.
Governments renegotiate infrastructure concessions routinely. Nobody proposed forcing Getlink to provide free access.
The supposed contradiction between public subsidy and competition is equally false.
Railways already combine regulated infrastructure, public-service contracts and private operators. Companies can compete to win a contract to operate a defined, fare-capped service. Competition occurs through tendering rather than by allowing several operators to duplicate half-empty trains at unregulated prices.
France, Belgium and the Netherlands would participate only if they judged the benefits worthwhile. Those benefits could include lower transport emissions, more visitors in both directions, higher rail use, reduced airport congestion and additional economic activity. The subsidy could be divided according to passenger origin, infrastructure use or emissions reductions so that no country simply funded British tourists.
You are entitled to argue that this coalition would be politically difficult or expensive. That is credible. But repeatedly calling negotiated policy change “illegal”, “impossible” or “state theft” merely assumes that every present treaty, concession and market arrangement must remain unchanged forever.
The climate does not care that existing commercial arrangements are convenient. If governments eventually conclude that some aviation activity is incompatible with their emissions limits, those arrangements will have to be lawfully amended, regulated, purchased or replaced.