From the dress to the guests, here’s the low-down on Prince Harry and Ms Meghan Markle’s big day.

A wedding is a time of laughter, joy and alcohol-fuelled mayhem. Or it is for most couples. Not if you are a prince, though, because then it is a military operation and a diplomatic nightmare. All three armed forces, the greater part of Thames Valley Police, the Special Air Service, the princes of the church, a battalion of peers and almost 1,000 guests will have to be conducted and corralled on the day Prince Harry and Ms Meghan Markle enter the state of holy matrimony.

It is enough to give a man vertigo. But the stately m’lords of England are not given to vertigo – or at least the ones that haven’t been done for tax fraud, murder or what have you – and it is a stately m’lord sorting out the whole business. The Lord Chamberlain, Earl Peel, and the comptroller, Lieutenant Colonel Sir Andrew Ford, are the poor devils tasked with it. It is as complicated as the maze at Hampton Court Palace, but without the benefit of the fresh air.

To ensure you don’t have the same headaches as the colonel and his lordship on 19 May, we have created a guide to the things royal-spotters should look out for.

It is the done thing among princes to wear uniform when they get hitched, a reminder of the close bond between the monarchy and the armed forces, of which the Queen is commander-in-chief. Prince Harry wore the uniform of an officer of the Blues and Royals, the second most senior regiment in the army, when his brother got spliced. But the word in the officers’ mess is that it is a bit infra dig to wear a guard’s officers uniform to your own nuptials, so he might go for the Marines, of which he is Captain General, or the Fleet Air Arm because he used to pilot Apaches. Either way, he will look better than most grooms – and he’ll have to. Nearly a billion people are likely to see him.

The main hurrah here is the dress, quite clearly. And at this moment in time we can only make an educated guess as to who is running it up. The Duchess of Cambridge, Ms Markle’s sister-in-law-to-be, famously wore Alexander McQueen, so that’s obviously out. What is probably in is Burberry or maybe Ralph & Russo, whose £56,000 couture dress Ms Markle posed in for her engagement pictures. It’s also odds on that somewhere on it there might be a Welsh leek, given her soon to be husband is Prince Henry of Wales (when the Queen was crowned, her dress had to accommodate all the emblems of the United Kingdom, the poor love). At any rate, it will be white, long and charming.

Most couples go for a Rolls-Royce or something similar to get them to and from their wedding, but that simply won’t do when your name is Windsor. The British public like a show, which, in the peculiar logic of monarchy, means the world’s most uncomfortable conveyance: a coach and six. If it is sunny, Prince Harry and Ms Markle will go in the Ascot Landau, which is a sort of convertible carriage, and if it rains, the Scottish State Coach. Lucky that they don’t have to take the Gold State Coach, which was described by King William IV like being on a ship “tossed in a rough sea” and by King George VI as “one of the most uncomfortable rides I have ever had in my life”.

If you think doing the guest list for your own nuptials is bad, spare a thought for the royal couple. It is a diplomatic farrago without end. For instance, the prince and former US president Mr Barack Obama are very pally, but to invite him would mean it would be very difficult to not invite President Donald Trump. When courtiers presented Prince William with the list of guests for his own wedding at Westminster Abbey, he had to appeal directly to the Queen – “I’ve got this list; not one person I know”. Prince Harry and Ms Markle have avoided this by inviting no politicians at all. Keep an eye out for the crowned heads of Europe – they will be a bit more nattily dressed than most – all of whom are the prince’s cousins, owing to the simple fact that Queen Victoria had nine children and they all married European royals.

Prince Harry and his wife-to-be have chosen St George’s Chapel, Windsor, for their nuptials and who can blame them? It is one of the most beautiful ecclesiastical buildings in all of England. Plus, the 14th-century Gothic masterpiece is relatively intimate, seating only 800. Poor Prince Charles had to have St Paul’s Cathedral so he could fit the 3,500 guests his position demanded he invite. Look out for the tombs of the 11 kings buried in St George’s and the heraldic banners on the roof, which are the arms of the Knights of the Garter, Britain’s senior order of chivalry.