Very convincing.
An English national public holiday was a crank position not long ago, a redundant non-problem. In large parts of the media, it probably still is. However, politics changes fast nowadays; this year's St. George's day was the most passionate in many years, for and against. It wasn’t about enthusiasm for a pious figure from history; the English national day is up for discussion because Britain has significant problems that need a political focus.
It looks odd that we don't have one; everywhere else does. Of the hundreds of countries in the world, only two don't have a national day - Denmark is the other. One proposal is to shift the May Day bank holiday, in England, to April 23rd. This would have the advantage of reminding people, whilst it is still needed, that we have left the EU. May Day itself is hardly unpolitical. May 1st has marked beginning of summer since pagan times, but that's not why Labour made it a public holiday in the Seventies. It was in solidarity with International Worker's Day, and towards anti-nationalist European integration. However, we have left; a popular, meaningful national festival on St. George's day would be a strong contrast, putting symbolic political distance between us and the sinister, unaccountable institutions of the European Union.
None of this, however, touches on why it really matters. A couple of decades ago, a national day was never even mentioned. Britain's stability seemed magically self-sustaining. A nebulous obligation to share our prosperity with the whole world seemed sort of reasonable, theoretically. Flag-waving was uncool, and contrary to the British way of things; enthusiasm for England was plebby and a bit naff.
Things have changed. It is not just that "the economy has slowed" or "growth has not met expectations." It is a time of catastrophically lowering expectations for all generations, not just economically, but in all areas of life. Times like these generate need for support for the sources of resilience; need which Britain's institutions and governing class are determined not to satisfy.
All EU countries have a national day holidays and no-one thinks the worse of them. English people have national passions just like everyone else - a glance at international sports shows that. However, English national feelings are derided as uniquely xenophobic. It's not a claim that makes rational sense, but the public discourse is about contempt, not argument.
Had the government wanted an English national day, there would have been one long ago. There has been a continuous campaign to denigrate nation-states in favour of supranational institutions: calling English patriotism xenophobic is probably part of that. Another way of saying the same thing is that St. George's Day is associated with "Far Right groups" and to encourage an English national day would be to encourage them. It is noticeable that evidence for this is rarely given, if ever. Given how much public debate relies on "Far Right groups" for rhetorical heavy lifting, this is a claim that should be subject to a lot more scrutiny.
There isn't space here to list the challenges facing Britain, and no-one thinks tinkering with public holidays is going to fix everything. But our cultural feelings matter just as much to us as other people's do to them. A proper English national day would be an acknowledgment of a moral and political constituency; one with serious political concerns, currently neglected, that should be addressed urgently.