Socially connected or not — and about 80 percent of today's members have blood links to prior ones — no one could or can be admitted without visiting on club day, proving himself a good storyteller and surviving not just a wave of pointed barbs but also a secret ballot (unanimous approval required).
Members don't need any special reason to reject an applicant, and everyone gets "balled," or "blackballed," at least once, Wilson says with a laugh.
"It's like getting married," adds member Jonathan Hyde of Gibson Island, whose late father, the architect Bryden Hyde, tried unsuccessfully for years to get him in before he was finally admitted. "You're going to be meeting with these people six times a year for the rest of your life. The last thing you want to do is make a mistake."
There's lots of history in the minutes — how members toasted the Duke of Cumberland for quashing the Jacobite rebellion (1746), delayed a meeting due to "the alarming situation … occasioned by an invasion of the British Fleet" (1777) and quarreled over slavery (1855) and secession (1861).
On a recent Thursday morning, history comes to life.
At the clubhouse, two flags — the British Royal Standard and the Maryland ensign — are crossed at the hearth, evoking the days when members hailed only the queen. An American flag recalls how members helped win the war for independence.
The day's steward, Sandy Clark of Easton, greets all members and guests, offering up conversation laced with history. A retired naval officer, he was commissioned aboard the USS Constitution, the frigate that club member and Navy hero Commodore Isaac Mayo commanded during the 1850s.
"It's an honor to have this duty," says Clark, 64, who has spent three days working with his wife to prepare the day's meal.
The clubhouse, which still lacks electricity or running water, is listed on the National Register of Historic Places, and it looks as it has for generations. A long table runs down the center. Mayo's sea chest stands in a corner. A framed, handwritten member log hangs on one wall.
Wilson, a retired printing executive, shows off the Chinese punch bowl acquired in 1799 — used to serve the club's secret drink, a blend of bourbon, rum, brandy and champagne so potent it must be diluted 2:1 with water.
"Have a taste, my boy," he says.
It's an hour or two until lunch, and everyone flocks outside for cocktails and conversation.
Half the members are politically liberal, half conservative, Wilson says, one reason they avoid discussing politics. But topics abound, from boat trips to boyhood larks.
Wilson spots the Rev. Bill Ticknor, longtime rector of St. James Episcopal Church in Lothian.
"The parson!" Wilson cries, and Ticknor, whose parish was founded as part of the Act of Establishment in 1695, unfurls a few tales of growing up in the Mount Royal section of Baltimore.
Ticknor approaches a member whose wife died just days before. He bows in sympathy.
"She was sick for a long time," the man says. "It was as though her batteries ran down." Another friend salutes his courage in coming.
And Geordie French of Monkton, 56, an Iglehart on his mother's side and a seventh-generation member, tells a visitor of his late grandfather, Joseph Iglehart, a financier who helped bring the Orioles to Baltimore in 1954 and soon became their largest shareholder.
"Ask the average fan who the [original] owner was, and they'll probably say Jerry Hoffberger," the team's majority owner from 1965 to 1979, he says, shrugging as he puffs a cigar. "But I won't bore you with that story."
Instead he flashes an iPhone photo — a group picture from a meeting in the 1990s. It's hard to miss one guest leaning against the clubhouse wall: Brooks Robinson, a family friend.
"Finest gentleman I've ever known," he says.
The earliest minutes were lost in the fire, but independent historical accounts suggest the Old South River Club predates England's oldest current social organization, White's, which was founded in 1698, and America's next-oldest, the State in Schuylkill Club of Philadelphia (1732).
Membership has waxed and waned over the years — it dropped to two at one point after the Civil War — but it has long held steady at 25. Openings occur when members die and are filled from a long waiting list.
When weighing an aspirant, the club considers family ties first, then such other factors as affability and achievement. There have been no female or nonwhite members, though no rules prohibit either.
"You pretty much have to show you can stand on your feet and tell a good story and be pleasant to everybody," says Wilson, whose father, John, was a member and whose mother, Emily, was the county's first female doctor.
Punch keeps flowing