Britain's Prime Minister David Cameron, exits his official residence at 10 Downing Street in London. (Lefteris Pitarakis/AP)

In a surprise sartorial development, David Cameron's wedding outfit has become one of the most scrutinized fashion decisions ahead of the royal event of the decade.

Earlier this week, Downing Street suggested that Cameron was shunning a suit with long tails in favor of a normal business suit, reportedly a first for a British prime minister attending a royal wedding.

Cameron, 44, has long sought to downplay his privileged upbringing, which matters hugely in a country where class confusingly permeates everything. The Eton and Oxford-educated premier often cycles to work. He wears shorts and sneakers on holiday. He flies on discount airlines. And when it came to Prince William and Kate Middleton's wedding, it seemed he was veering towards casual side of acceptability.

"If Cameron had his way, he'd turn up at the wedding in tracky bottoms and a string vest, burping cider fumes as he sat down," sniffed the Daily Mail.

Unnamed "friends" of Cameron were quoted in the press saying the prime minister didn't want to be photographed on the steps of Westminster Abbey in attire that made him look too posh (raising the question: how posh is too posh for a royal wedding?). And besides, the official invites said the guests could wear a uniform, morning coat ('tails') or a lounge suit ('business suit').

But would the head of Her Majesty's government in the United Kingdom really step out in front of a televised audience of 2 billion in his work clothes? What would foreign royals draped in traditional robes think? Would it be awkward if David Beckham and Elton John rocked up in top hats and tails?

Cue outrage.

Or, because this is Britain, letter writing.

"People don't care where he comes from or that he might be a toff," wrote James Charrington in the Daily Telegraph, referring to Cameron's upper-class background. "Show the public and the future king and his bride some respect and turn up to the royal wedding in the correct attire - a morning coat."

In a letter sent to the Express newspaper, S McCormick from Glasgow wrote: "What ‘Dave’ doesn't seem to realize is that weddings are precisely the occasions when we genuine commoners get all dressed up. He's just underlining how out of touch he is."

On Monday, Cameron was reportedly planning to wear a suit to the wedding. By the end of the week, after many strongly-worded letters and much tut-tutting, he was said to be wearing tails. British press reports said that Downing Street blamed the confusion on an uninformed aide wrongly briefing reporters.

A Downing Street official on Friday said he "wouldn't confirm" if Cameron was leaning more towards a suit or coattails (or a top hat, for that matter).

But either way, it seems that Kate Middleton won't be the only one whose sartorial choices will be endlessly scrutinized on her wedding day.