Steven Joyce will not be along on this trip. So I will address this directly.
Her Majesty has a steel-trap mind and has heaps of experience with Prime Ministers so she will go for topics of common interest.
In no particular order, I'm guessing electricity prices will be on the agenda. The Queen is famously economical with power at Balmoral and fires up the entire joint with two-bar electric heaters. There's a decent chance HRH might ask about the cost of heating New Zealand homes over winter.
Mr Key, for the love of God, don't let Her Majesty know the Lotto-figure power bills we pay or she will think we common folk are idiots.
Even worse, don't let the Queen know that the Government has sold or is in the process of selling these same power companies which extort huge profits from we compliant common folk. Her Majesty would then think New Zealand's Prime Minister is an idiot.
Here's the thing, Sparky, the Queen's forebears hung on to their family silver as if the quality of life for royal generations to come depended on it.
Turns out it did. The Royal Family's Crown Estate was last valued at more than 18 billion quid and rising, what with land prices in the UK nearly as over-heated as in Auckland.
Another obvious common talking point will be family. Go delicately with this one, Mr Key.
If the Queen starts telling Stephie and Max who married who in her pan-European bitsa family before 1917, fake a heart attack. For everyone's sake.
Talk of Prince Bertie alone will loosen a closet full of German skeletons, and the whole surname change to Windsor will come up. You don't want that. There's also Prince Philip's way-too-close connection with Queen Victoria who is also the Queen's great-great-grandma.
I defy any young adult educated by regularly paid teachers not to soon work out how the royal family produced such outstanding ears.
The Queen has a stunning memory. HRH would probably recall if she had shares in a vineyard, or a state rail company, that kind of thing.
The Queen will totes know her anti-apartheid view given her infamous stoush with Margaret Thatcher over the then Brit PM's refusal to sanction South Africa. Just a heads-up.
So both you and the Queen's best bet for common ground, without worry, would be gambling? That's a yes on paper but not in the fine print. Granted, the Queen supports horse-racing almost as much as you support casinos but HRH has skin in the game. She gambles with her own money. No contra deal there. It's not the Queen's MO.
Her Majesty is a stickler about traditions, rules and laws. She'll go on and on about them, I bet. The Queen probably knows all about democracy as well, seeing as it's industry-related for her. This coming weekend could be an excellent opportunity to learn some of this democracy stuff.
If all else fails, and this fifth meeting with the Queen turns to cack, there is one area of unassailable similarity between the UK and Aotearoa/New Zealand. England isn't egalitarian, and, ah boo, neither is New Zealand. Snap.
Social mobility is all but gone in the UK. New Zealand can put its hand up to that too.
Shriek and roll about and high five.
Relax away, Mr Key, on this one-off experience and don't forget the name of the corgi who died after being filmed with Daniel Craig.
That would be the greatest boo-boo of the lot. Good luck with that.