LONDON — Volunteers handed out stickers saying “I Queued in the Rain” for throngs of tennis fans waiting four or five hours in long lines for the gates to open into one of the world’s four grand slam tennis tournaments, an extravaganza in 19 courts at Wimbledon Park.

The mood of the thousands lined up in eight long queues stretching across green fields beyond the courts was exuberant, friendly, patient, and filled with good-natured optimism when the lines began slowly inching forward. 

Inside, standing in still more queues to get into individual matches, not including those in Centre Court or courts nos. 1 and 2, for which special tickets had to be purchased well in advance,  the mood was infectious. It was as though people were all attending one huge party or celebration, with plenty of shops and dining areas ready to contribute to the fun.

In the midst of a match at court no. 18, a Bulgarian, Grigor Dimitrov, was about to serve to Sho Shimabukuro, of Japan, when two 60-something spectators, a man and a woman, leaped over the railing and began tossing gold-colored bits of confetti and blue pieces of a jigsaw puzzle. Then they held up placards saying,  “Just Stop Oil.”

As security officers and stewards hustled them away, crowd members booed and shouted epithets. “Lock them up,” “Put them in handcuffs,” and “Send them to jail” were among the shouts that I heard as the pair were hustled off. It was the latest of a series of protests by the anti-oil activists as they demanded severe sanctions on the use of oil.

Judging from the protests on court 18, the movement may be having the opposite effect. In the stands, spectators called the protesters spoilsports, so full of their own righteousness as to disregard the emotions of those who had waited hours to glimpse a few matches. One of the hundreds of “honorary stewards” — a retired schoolteacher — decried the protest as defeating the purposes of the activists.

“They’re losing whatever support they had,” he told me. The question, though, was how they got through rigorous security checks that resemble the treatment of would-be airline passengers. One theory was they painted the posters after getting past security and picked up the jigsaw puzzle in one of the many shops inside the park. “They’re everywhere,” he said. “It’s very hard to stop them. There’s not much to do.“ 

Members of the movement in recent months have thrown tomato soup at a painting by Van Gogh in London’s National Gallery, have thrown ketchup at other classic works, and have prostrated themselves in front of trucks, blocked traffic, and painted slogans on buildings. So far they’ve suffered no casualties and done little damage — even to the Van Gogh painting.

As crowds surged into Wimbledon, the protest was remembered largely in newspaper articles. Mr. Dmitrov said he was tempted to go after the activists but thought better of it. The protest, he said, distracted his focus and broke up his rhythm as he was about to serve, but did not stop him from defeating his Japanese opponents in three straight sets.