What advice do you offer a family about to spend the weekend with the royals?
Be polite, don't expect to leave on a first-name basis, and leave your jeans at home, says Britain's leading expert on royal etiquette.
William Hanson says a weekend with the royals at Balmoral is not quite the social minefield one might think, but there are a few strict rules Prime Minister John Key and his family would be wise to follow.
Key, his wife Bronagh, daughter Stephie and son Max will be spending this weekend as guests of the Queen at her private residence at Balmoral in Scotland - a rare honour for leaders outside Britain.
However, there are hidden trapdoors when it comes to decorum.
Simple common courtesy and politeness will go a long way, Hanson says.
"It's not particularly a minefield. If you were staying at anybody's house you just have to be aware of good etiquette really.
"The fact that it's the Queen, yes OK, it's very important but really Balmoral is the family home. It is one of the Queen's private residences, and the atmosphere there is very much relaxed."
He says the invitation is a "warm nod" to New Zealand.
"This whole visit is obviously Britain officially acknowledging New Zealand, and rightly so.
"I think it's a great honour, really, for the whole family to be invited, and I think why the whole family has been invited is because Balmoral is very much like Sandringham in that it's a family home."
But the visit gives a whole new meaning to the expression "kids, on your best behaviour".
Hanson has offered his guide of "do's and don'ts" to help the Keys through their royal jaunt to the countryside.
KNOW YOUR PLACE
Tempting as it is while standing around the barbecue with the Duke of Edinburgh, never forget who you are. Or, rather, who they are.
Hanson says Balmoral is famous for its royal barbecues, where the royals themselves like to take over the tongs.
"It is very, very laidback. With that said, the trap is obviously to become so laidback that you start calling them Elizabeth and Philip. Obviously that is not the done thing - they are still the Queen and Duke of Edinburgh," he says.
"[The correct way] would still be Your Majesty followed by Ma'am or Your Royal Highness the Duke of Edinburgh followed by Sir."
The same applies to the Duke and Duchess of Cambridge, and of course, Prince George.
"It would still be your Royal Highness and Sir to the baby," Hanson says.
SHAKING HANDS, HOLDING BABIES
They're tools in every good politician's arsenal, but an unexpected handshake and quick pose with a baby won't be well-received here. That is, not unless the royal hand, or baby, is offered first, and there is a good chance Prince George and his parents will be present.
Never ask to cuddle the royal baby, says Hanson.
"You would wait to be asked to hold the royal baby, rather than going 'can I hold him', you would wait until it was offered, and I'm sure it would be.
"But they [the Duke and Duchess of Cambridge] are more relaxed than the Queen and the Duke of Edinburgh, just don't overstep that mark."
The British tabloids have reported the newest royal and his parents will be at Balmoral this weekend.
British newspaper The Daily Mirror said William and Kate flew with 7-week-old George to Balmoral earlier this week for the royal family's annual Highland Fling and were planning to stay for a week.
It will be a family affair, with Prince Charles and his wife, the Duchess of Cornwall, Camilla, thought to be staying at Birkhall, their home next to Balmoral. One report suggested Prince Andrew and daughters Beatrice and Eugenie were also present. Key won't comment - it is a breach of protocol to discuss the other guests.
BEST DRESSED IS BEST
Only black tie and full-length dresses will do for dinner. Aside from the royal barbecue, where casual attire is welcomed - though never denim - most other evening dinners are formal.
Key said both Bronagh and Stephie had to buy new dresses for the weekend. Teenage son Max bought a dinner suit.
Balmoral is a country estate, so during the day the Keys will be taking part in country pursuits, Hanson says.
"It's in Aberdeenshire, in Scotland, and there is no big city nearby. It is country pursuits. It is things like deerstalking, it's fishing, walking, hiking, walking the dogs ... There could be a bit of shooting with the Duke of Edinburgh or some of the younger members of the household."
It was important to pack warm clothes appropriate for those undertakings, though again, never denim.
And the recent artistic portraits of Stephie Key? Hanson says they are unlikely to be raised.
"The Queen will make no mention of this, I think that is key. The Queen will not have an opinion on it, and probably will, in true British style, just sweep it under the carpet and carry on."
So along with various fast food items and sea life, did we mention denim was out?
ENJOY YOUR QUARTERS
Hanson says there is probably nothing that would please the Queen and Duke of Edinburgh more than sharing the history of their home.
A bit of research before visiting wouldn't go amiss, but there is no greater resource on Balmoral than the proprietors themselves.
"It would be nice to do a little bit of background research on Balmoral, it provides topics of conversation.
"But I'm sure the Queen and the Duke of Edinburgh will love talking about the history of Balmoral, and telling interesting stories about it."
For those who aren't privy to the royal account, the estate was bought in 1848 after Queen Victoria and Prince Albert fell in love with the Scottish Highlands.
The castle was built between 1853 and 1856, after the original house was deemed too small for the royal household. George V made improvements in the '20s, including formal gardens. More and more land was bought and today the estate spans an enormous 49,000 acres.
The cold may be a problem for the Keys (more used to their modern Parnell abode) - bedrooms have only old-fashioned one or two-bar electric heaters.
But should they need a hot water bottle, there will be someone at their beck and call at all times.
Upon arrival, each of the Keys will have their own valet and maid provided if they so wish.
"If the prime minister is not bringing his own staff, they are given staff from the royal household and so they can expect their suitcases to be unpacked for them. Everything to be beautifully hung, and also suitcase re-packed at the end of the stay," Hanson says.
And if you find someone wanting to iron your underpants disconcerting?
"Don't worry about it - there are worse things to happen in life. And I think everybody likes to be fussed over, don't they?"
WHAT GOES ON TOUR, STAYS THERE
The fastest way to be left off the invitation list in future is to blab about your weekend with the royals.
Key refused to comment when asked which members of the royal family might be staying at Balmoral over the weekend and is expected to be just as tight-lipped after leaving.
A few generalities are fine - a blow-by-blow account of the weekend is a definite no-no.
- The Dominion Post
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