0600 (London Time): Police enforce road closures throughout central London.
0800-0900: Announcement expected from Buckingham Palace on any titles that Queen Elizabeth will bestow on Prince William and Catherine Middleton. (Tricky stuff; if William declines a title, then his wife becomes the oddly named “Princess William of Wales.’’)
0900-0945: All “ordinary’’ guests arrive (via Great North Door of Westminster Abbey).
0950: VVIP guests start arriving — Governor Generals and foreign Prime Ministers via Great West Door. Members of the Diplomatic Corps via the GND.
1025: Large tranche of “junior royals’’ depart Buckingham Palace — in posh minibuses. These are cousins of Queen, the Kents, Gloucesters, Zara & Tindall, et. al. (Yes, “posh minibuses’’ is in the original. Zara Phillips is Prince Charles’s “high-spirited’’ [read: spoiled rotten] niece. Tindall is her rugby-playing fiancé.)
1030: Her Majesty’s Bodyguards of the Honourable Corps for Gentlemen at Arms and the Queen’s Bodyguard of the Yeoman of the Guard process up through the Abbey. (Ah, the Python-ness of it all. . .)
1040: Senior royals arrive (York/Wessex /Princess Royal) — welcomed by Dean and Chapter, conducted to seats by Gentlemen Ushers. (“Chapter’’ refers to the Canons of the Abbey. Senior royals are real royals, e.g. Prince Andrew — “Randy Andy’’ — who is in a mess of financial trouble, as usual. He will not be accompanied by his ex-wife, former WeightWatchers spokeswoman Sarah Ferguson, who has her own public woes to contend with.)
1042: Prince Charles and Camilla arrive at GWD and wait at door until Queen and Duke arrive. (“Rottweiler’’ alert!)
1045: Queen and Duke arrive. (FANFARE)
1048: Pippa Middleton, bridesmaids, and page boys depart from Goring hotel in posh minibus. (That phrase again. Pippa is Kate’s sister, one of many bizarrely named Brit aristos heading for the Abbey. Guests include the P.G. Woodhouse-worthy Davina Duckworth-Chad and Isabella Anstruther-Gough-Calthorpe. William’s nanny Tiggy Legge-Bourke, nicknamed after Beatrix Potter’s lovable hedgehog, Mrs. Tiggy Winkle, will surely attend. Her infant son is a royal page.)
1100: WEDDING CEREMONY (Order of service details to be released on the evening of April 27.)
1205: Service concludes with the signing of register, to take place privately in the Shrine of Edward the Confessor.
1215: Royal party form up outside Abbey as newlyweds get into first carriage.
(The Timeline offers a complicated hierarchy of carriages. William and Kate will journey to Buckingham Palace in the 1902 State Landau, with a mounted escort behind them. Then come the escort-less Prince Harry, Pippa M., bridesmaids, et. al. in two Ascot Landau carriages. Queen Elizabeth and her son Charles will follow in separate Semi-State Landaus. A dodgy -looking website explains that the Landaus are kept in the Royal Mews, which is “part of the Lord Chamberlain’s Office and is run by the Royal Equerry.’’)
Junior royals and all others — will board posh minibuses. (But of course.)
1230: Royal couple arrive through gates of Buckingham Palace. (Welsh Guards will provide Guard of Honour on forecourt of BP for their return.)
1325: Balcony moment (likely order: William & Kate, followed by Queen and Duke, followed by both families — but not aunts and uncles. Then they will collapse back inside in reverse order.)
(Comes now the tightly scheduled Royal Kiss: You’re trying to get to work on the Southeast Expressway; William is having a snog. In fatter years, the couple might sail off for a dreamy honeymoon on the royal yacht Britannia . Alas, Tony Blair’s Labor government decommissioned the pricey tub in 1997. Royal marriage just isn’t what it used to be.)
Alex Beam is a Globe columnist. His e-dress is beam@globe.com.