A soldier from the Irish Guards is helped from the Victoria Barracks parade ground yesterday

THEY are the final pieces of royal wedding protocol for every Guardsman: faint with dignity and if your bladder can’t take the strain of four hours standing to attention, think of England and don’t leave your post. The troops who will line the route of the royal procession and escort the royal couple, many of them Foot Guards who will be wearing sweltering scarlet coats and bearskin hats, have been given orders that they must “faint to attention” if the heat proves too much for them next Friday. Some 1,500 military personnel are training for what the Armed Forces promise will be a minutely choreographed display of precision and ceremony. The route has already been measured by the Army’s senior ceremonial expert, Garrison Sergeant-Major Billy Mott OBE, who pronounces it precisely 1,409 paces of 30 inches after walking it several times with a drill sergeant’s pace stick (akin to a giant pair of compasses).

The planning, Sergeant-Major Mott says, has been worked out to the second rather than the minute. And the troops – who will include six different bands, 200 horsemen and 1,200 servicemen on foot – are carrying out a month’s training with a full dress rehearsal at 4am one day next week. The men of the Welsh Guards, 390 of whom will be involved, have already been issued with new boots and told to spend three days buffing and polishing them with wax and “four to five” tins of polish for a mirror-like finish. The night before the wedding their orders are to shower with their bearskins and shampoo them before drying them overnight and combing them to a perfect finish the next morning. For those who find the heat or the weight of the occasion too much, their orders are clear. There is to be no crabbing sideways or swaying and certainly no dropping your rifle, going down on one knee or putting a hand down. Instead true grit is displayed by those soldiers who can topple forward face first while still holding their bayonet-tipped rifles. “You have to faint to attention,” says Major Dai Bevan, who will lead the 101-strong Guard of Honour from the Welsh Guards. “It will probably involve a broken nose and a whole lot of missing teeth.”

Special contempt will be reserved for anyone who falls over on his back. The entire uniform – which has 11 layers of cloth in the tunic – is designed not to show sweat patches. The troops have been told to offset the risk of fainting while on duty by ensuring that the leather band on their bearskin is not too tight so that their heads can expand in the heat and by drinking up to five litres of water beforehand. But this brings with it another set of problems. For those Guardsmen who misjudge the intake of fluids leaving their post is not an option. “You can hear lads groaning behind you,” says Guardsman Bryce Pounder, 25, of the Scots Guards and a veteran of last year’s Trooping The Colour parade. However at four hours, the royal wedding will be an hour longer than Trooping The Colour. If the pressure on bladders is too much then the thick barathea wool trousers they wear are sufficiently dark to cover their embarrassment, according to Guardsman Shaun Marsden, 25. “You might get a few little puddles,” he says.

Sergeant-Major Mott, the Army’s fearsome chief drill instructor, will be crucial to the smooth running of next week’s event. He was a member of the Honour Guard at the wedding of the Prince of Wales and Lady Diana Spencer in 1981. His prescription for the day includes a five-mile morning run, a good breakfast, plenty of water and a lot of toe wiggling and calf-tensing. “If you are resting on your heels the blood doesn’t flow back to the brain,” he barks. Major Bevan adds: “You shouldn’t faint if you stay alert and keep concentrating. “I do equations.” For those playing musical instruments there is the prospect of playing eight marches and 25 “showstopper” tunes to entertain an estimated 600,000 people along The Mall through the wedding ceremony.