These are tricky times for the tactile among us; a shoulder squeeze capable of causing an ethical quandary, our phones now being the recipients of the majority of our physical touch. Some comfort, then, to see that the royals, arbiters of protocol and proper-ness, are doing away with the invisible bargepole previously erected between them and embracing a touchy-feelier dawn.
It all started in 2009 when then First Lady Michelle Obama rested a shapely arm on Her Majesty's back – a gesture that was, at the time, dubbed an "epic faux pas", yet turned out the sovereign actually rather liked. And the younger royals are now at it too, most recently seen last weekend in the Duke of Cambridge's gentle placing of a hand on his wife's back; the kind of public display of affection the pair had previously eschewed.
The Sussexes are to thank for this hike in haptics, having significantly upped the PDA-ante since their wedding in May (no doubt helped by Meghan Markle's Hollywood credentials) and seen in a similar paw-just-above-posterior embrace on multiple occasions. Not to mention cosying up under an umbrella on their royal tour in Australia, strolling arm in arm on a forest walk in New Zealand and smooching at the races.
Among couples, then, it appears that PDAs have gone full circle, transitioning seamlessly from Deeply Uncool to Quite Nice Actually And Not Worth All That Fuss We Used to Make About How Embarrassing and Unnecessary They Are. Yet when it comes to social events, the workplace or even the gym, the weight of #MeToo looms large, and it's hard to know what – if anything – is up for grabs anymore.
So what are the new rules for public petting?
Glasses being constantly refilled, music and frivolity in the air - the number of ways to slip up at a social gathering are infinite, not least when you throw a monarch into the mix, as Michelle Obama found almost a decade ago. It's easy to see how it all unfolded, when you think about it – having mentally run through all the small talk options ahead of time, convinced yourself that Her Highness would rather something more whimsical than yet another clunky epithet about corgis, the unseasonal weather we've been having or bucket hats, you decide to freewheel it.
Then lo and behold, you end up bonding over how uncomfortable your respective shoes are and suddenly you're clutching the monarch of 16 nations as if she's your next door neighbour mid-rendition of Auld Lang Syne.
Contrary to those who criticised the over-familiarity, the Queen was a fan, responding by "pull[ing] closer, resting a gloved hand lightly on the small of my back," Obama describes in her new memoir, Becoming.
We've all likely got too friendly when dressed in our best and caught up in the occasion, going in for a squeeze when getting on roaringly with a new acquaintance, but take things too far and you'll be struck off the invite list until the end of time.
Do: Keep it jovial, clink away and extend an arm to someone you're getting on exceptionally well with – provided you're only making contact from the waist up.
Don't: Slosh red wine all down their front and start dabbing at verboten areas suggestively with a napkin.
A steamy-mirrored hot yoga studio, a diligent instructor's fingers lightly manoeuvring your hips as he corrects your downward dog - given the myriad #MeToo movements that exposed overt handsiness in every arena it is a wonder, perhaps, that the land of the sweat-flecked and tightly clothed has (thus far) managed to escape scot-free. And mat-dwellers are keen to keep things that way, now even enlisting 'consent cards' - which say either 'Yes, I would like hands-on assistance' or 'Get your filthy mitts off my shavasana' (we might be paraphrasing) to ensure no foul play throws their practice off-piste.
When does a trainer improving your form veer from thorough to thoroughly unseemly?
Do: Allow a guiding palm to help you find the right position. Just the once, mind.
Don't: Make excuses if hands keep finding themselves where they shouldn't. And if there are routine suggestions to disrobe due to 'broken air conditioning', run.
Hug or handshake at parents' evening? And at the school gates? Do you buy the teacher a present at the end of the year by way of apology for your perma-tantrum throwing child, or is that merely a ruse for flirtation? Tricksy, though if your otherwise disinterested husband suggests an especially lavish gift for the blonde form tutor who's partial to a short skirt, that could be a giveaway.
There's a lot at stake here, after all - do wrong by the teachers, and there'll be a black mark against your child's name forever; do so against fellow parents, and such a stain will besmirch the record of both your offspring and yourself, which is obviously worse.
So when it comes to fellow parents at drop-off, err on the side of caution again - no cheek-kissing for the dads if you're just extending stiff hugs to the mums; you'll only end up the subject of bitchy WhatsApp group chats afterwards.
Do: Extend the same greeting - hug, single kiss, whichever works – to all.
Don't: Enter into private conversations via text with other mums' husbands. Guaranteed to make you look guilty, even if it's only to swap recipe notes for Delia Smith's shepherd's pie.
An ill-timed reach for the milk, welcoming a colleague back after maternity leave, navigating the narrow corner by the filing cabinets: the office has become a veritable viper's nest for encounters of the awkward kind, with every once-innocuous interaction now probable cause for a lengthy HR report.
Though the blanket (and likely quite wise) rule of thumb might be Avoid Colleague-Based Human Contact At All Costs Ever these things, as our esteemed global leaders show, leave us firmly in the grey area. Take, for instance, Emmanuel Macron and Angela Merkel clasping one another's hands at the Armistice memorial last weekend, posted on social media with a single word - 'united' - the perfect emblem of just how potent a certain closeness between colleagues can be.
That is until you consult the vast, vast evidence to the contrary: Macron clutching Donald Trump's knee at the Elysée Palace; the President gripping our own Prime Minister's paws on a frankly worrisome number of occasions; the ill-fated encounter between Jeremy Corbyn and Emily Thornberry that the history books will surely record as the 'Unfortunate Boob-Five of 2017.' Toe-curling, every last one.
Do: Keep things friendly – without touching, where possible.
Don't: Grab, grip or grasp – or, worse still, follow one of the aforementioned clangers up with 'ha ha, don't go referring me to management now, will you! Will you?'
We have established that it is now acceptable to publicly demonstrate that you and your partner are not physically repulsed by one another, and both Princes have been doing a fine line in showing affection that doesn't descend into downright filth. Yet while a certain level of tactileness is fine, anything OTT – that's Over the Top Touching – remains out of bounds.
Do: A kiss or placing of a hand on your beloved – we're permitting a gentle perch on the bottom, even, we're not prudes – provided it's of a nature you wouldn't mind your own parents witnessing.
Don't: Get carried away. Finding your partner irresistible after a long period together is to be admired – but ideally by one another alone, and behind closed doors.