TMZ originally stood for Thirty-Mile Zone, a swath of Los Angeles covering the entertainment industry, but now the abbreviation means something else and is prompting howls 5,000 miles away in Buckingham Palace.

TMZ.com took its name from the cartographic reference, but the news website is in the business of getting global clicks through scoops on celebrities, athletes, tycoons – and royalty.

Its clout was on neon-flashing display this week with a series of exclusives about whether Meghan Markle’s father, Thomas Markle, would attend her marriage to Prince Harry at Windsor Castle on Saturday.

The will-he-won’t-he saga (conclusion: he won’t) gripped readers, upended the British royal family’s choreographed preparations and sent other media outlets scrambling to follow up TMZ’s daily updates.

The House of Windsor and the hounds of Fleet Street, humbled by an operation based at a former post office distribution centre with darkened windows in an unhip part of LA – how did that happen?

The short answer: Harvey Levin.

The lawyer turned TV journalist is TMZ’s founder and svengali, a driven force who oversees a legion of reporters, videographers and producers tasked with uncovering gossip, scandal and occasional agenda-setting journalistic coups.

Sources seem to be everywhere – courthouses, hospitals, ambulances, airports, airport gift stores, hotels, motels, police stations, lawyers’ offices, elevators, beaches, limousines, nightclubs, streets outside nightclubs. And they often bear documents, photographs, audio recordings or videos.

This surveillance apparatus has remade the rules of celebrity. Drip-drip revelations about Lindsay Lohan’s trial for theft in 2011 prompted one judge to compare TMZ to the CIA.

The site is respected, imitated, feared and loathed – but never ignored.

“Harvey has amazing contacts and they just keep plugging away,” said David Thompson, a former LA-based editor for OK! magazine who now runs a public relations firm, Cavalry PR. “They have the manpower. They’re not just about repeating gossip because they don’t stop until they get to the source of the story.”

Fobbing off TMZ tends to not work, said Thompson. “With someone like TMZ you’re usually not helping the client if you’re a publicist and all you do is say no comment. It’s going to turn out better in the long run if you’re able to work with them.”

That wasn’t an option for Buckingham Palace after it left Markle’s father, a retired lighting director, unprepared and ill-equipped to handle the paparazzi who staked out his home in Mexico.

The 73-year-old cracked under the strain, collaborated in clumsily staged photos and suffered heart problems and emotional agony, putting in doubt whether he would walk his daughter down the aisle.

TMZ swept in and got a scoop on each twist, turning TMZ into the Thomas Markle zigzag chronicles – essential reading for royal watchers and the palace’s hapless wedding planners.

“We didn’t pay him anything, he didn’t ask for anything,” Levin said in one of the site’s daily syndicated TV shows. A reporter contacted Prince Harry’s future father-in-law and won his trust, simple as that, said Levin.

TMZ’s founder is more circumspect with reporters. Contacted for this article, Levin referred the Guardian to a publicist who said no company representative was available for interview.

Much of TMZ’s success has a simple explanation: boots on the ground. In an era of shrivelling newsrooms it stations teams in courthouses to scan dockets and deploys others across LA, chasing tips and rumours for celebrity news big and small.

“TMZ are out there on the street with video cameras pouncing on B/C/D-list celebs,” said one former reporter for Mail Online’s LA office. Other outlets, in contrast, “mainly just write around sets of pics that come in from freelance photographers”.

TMZ cultivates multiple sources – defence lawyers, prosecutors, court clerks, bellhops, chauffeurs, chambermaids, barmen, police, paramedics – and lubricates, when necessary, with cash.

Levin, 67, founded the site in 2005 with a resolve to smash, as he saw it, a corrupt cocoon of fixers and enablers who hushed up celebrity crimes, follies and misdemeanors.

Scoops flowed: Mel Gibson’s antisemitic rant, Michael Richards’s racist diatribe, Michael Jackson’s death (reported 18 minutes after he stopped breathing), Chris Brown beating up Rihanna, Prince’s death, Solange Knowles assaulting Jay-Z.

A 24-hour ticker-tape of revelations that stoked anxiety in Hollywood. Rumours spread of a TMZ vault with salacious material withheld from publication as long as celebrities gave up other secrets.

One bodyguard, speaking on condition of anonymity, assumed – not necessarily correctly – that TMZ was the main client for the paparazzi who stalk his client, a singer. “Whenever she’s ready to leave, they’re there.”

Some celebrities and publicists have adapted by discreetly collaborating with TMZ, which sometimes sheathes the sword for fawning stories and flattering photos.

Others wage a cold war and denounce Levin as Frankenstein, or worse. “He is a festering boil on the anus of American media,” Alec Baldwin told the New Yorker.

Prince Harry may have had choice words in 2012 after TMZ published pictures of him partying naked in Las Vegas.

Levin, a fitness fanatic who works out before dawn, takes special pride in consequential scoops, such as a video of US marines urinating on dead insurgents in Afghanistan or a bailed-out bank blowing millions on a party. Some stories fuel national debates, such as Kanye West declaring slavery to be a choice, or the NFL star Ray Rice knocking out his fiancee.

Some TMZers, as staffers are known, describe a febrile atmosphere, gruelling hours and a tough culture in their Playa Vista headquarters, with Levin directing operations from a raised desk in the middle of the newsroom.

“Make sure you have a thick skin and a tolerance for insanity,” advised one post on Glassdoor, a website which lets employees and ex-employees rate workplaces. “This is a one-man show, and all authority and decisions flow through him.”

An absolute monarch presiding over a digital kingdom, Levin doesn’t need to show up at Windsor Castle. He’s already crashed the wedding.