While it may seem unlikely that you’ll ever meet a member of the royal family, it pays to be prepared for such an eventuality.
The protocol for such meetings varies according to the venue: in a supermarket, for instance, the correct form of address is “ma’am”, irrespective of the royal involved, and you should offer to push their trolley as well. Bowing and curtseying is only called for when meetings take place in churches, hospitals, chicken processing plants or bookmakers.
Shaking hands is permitted when accompanied by children, firemen or vegetables, but not when in the company of railway porters, glassblowers or snakes. Offering to polish the sovereign’s shoes will be taken as a sign of fealty, but offering to comb their hair will lead to lengthy incarceration in the Tower of London. If the royal coughs, burps, sneezes or farts, you should do likewise, but in a deferential manner.
You are permitted to wear your own crown or tiara, but other forms of headwear, including toupees, laurel wreathes and tarpaulins are deemed disrespectful and you could be flogged. On no account should you utter a sentence which includes the words “So how come you’ve got loads of massive houses, thousands of acres of land, and a priceless art collection, and we still give you and your hangers-on millions of quid every year, you in-bred German parasites.”