Wayne Rooney, right, gives Manchester United a large dose of star power as it travels the U.S. on its most recent exhibition tour. (Nam Y. Huh/AP)

The Sunday crowd in the pub in London was small, which is probably how the old man heard me. The bartender, while pouring a drink, asked what brought me to England.

“Here for sightseeing and a couple Manchester United matches,” I told him.

To which the man with gray hair and tweed suit — he could have been Tink from the “Lovejoy” mysteries — grabbed my arm and looked me in the eye.

“Please,” he said. “Don’t use that language in here.”

That’s just one hazard to being a United fan. There are others, like the constant comparisons to being a New York Yankees fan.

The Yankees comparison isn’t bad. Each is a legendary franchise with a history of outstanding performances in the tightest, most intense circumstances. (Except, I should add, if the opponent is Barcelona and it’s a Champions League final.)

“While other teams are too tight to breathe in a crisis,” Post columnist Thomas Boswell once wrote, “the Yankees spit their tobacco and smooth the dirt with their spikes.”

In the 1995-96 season, a writer for the Guardian predicted — correctly — that Manchester United would overcome a 13-point deficit and win the title over Newcastle United.

“Not only do they cope with the tension, they appear to enjoy it,” Vincent Hanna wrote. “The fans, the manager and Manchester also have been infected with serenity sickness. Win or lose, they are not afraid.”

Life as a Barcelona fan must stink. In the Spanish league, only Real Madrid can match Barca’s talent and coaching. The rest have no chance. Think Sherlock Holmes and Moriarity, or Smokey against the Bandit. Meetings with anyone else don’t always get the juices flowing.

United, meantime, has more rivals than Batman in that old TV series; every Saturday is fraught with tension. Liverpool is rejuvenated under Manager Kenny Dalglish and the most ear-splitting home fans in England; Chelsea and Manchester City have billionaire owners and rosters teeming with talent.

Arsenal plays excellent soccer, albeit perhaps a little too dainty. Tottenham Hotspur is in the mold of Arsenal, with slightly less skill and slightly more willpower.

The Premier League for United is akin to being the titular street gang from Walter Hill’s 1979 movie “The Warriors.” To reach the promised land, United has to travel through a lot of people who want a pound of flesh.

The Warriors made it to Coney Island safely. And United has navigated the minefield a few times as well. It won its 19th league championship last year, the most in England.

Barcelona fans gather at a special bar in D.C. I think that’s great, especially as it’s an English-themed bar. United fans don’t need their own bar. Walk into Lucky Bar or Fado or Summer’s or Flanagan’s Harp and Fiddle on a match day and you’ll find plenty of other Reds.

It’s not surprising. United released a study earlier this summer: It has 330 million fans worldwide. Wonder how many the Yankees have? Or Barcelona?

The writer is a copy editor and reporter for The Post’s Sports department.