Taylor Swift's London 'Eras' Show Brings Out Travis, Jason and Kylie Kelce

Taylor Swift's ready to have tea and crumpets with her man Travis Kelce after her show tonight ... 'cause he's out in London to support her -- and, it looks like it's a double date.

The singer-songwriter took the stage in England's capital at Wembley Stadium ... and, TK's front and center, dapping up his friends and signing autographs for fans in the crowd -- a real joyous scene.

BTW ... Travis is definitely bringing a taste of America across the pond -- 'cause he's got a U.S.A. Olympic cap on, so the dude's looking pretty patriotic.

And, Wembley looks like a family affair too ... 'cause Travis' big bro Jason and his wife Kylie pulled up to show their support for the Chiefs tight end's main squeeze.

Jason -- whose appearance Friday marked both his and Kylie's first during the "Eras" tour -- got into the spirit of the event with friendship bracelets running from his wrist to the middle of his forearm. He tossed the bracelets to fans in the crowd ... sharing the Swiftie love.

While Travis has regularly attended Taylor's shows since the two went public with their relationship last year ... he hasn't popped up at her concerts much recently.

We last saw him cheering her on alongside Bradley Cooper and Gigi Hadid in Paris before he and TS went on a mini European vacay ... full of romantic dinners, boat rides -- and resulting in what looked like a hickey on Taylor's neck!

Travis has kept busy though ... recording his "New Heights" podcast with Jason and visiting the White House before receiving his third Super Bowl ring.

But, the NFL season's starting again soon ... so Travis will likely have to put the jet-setting on pause for a bit to make sure he's ready for the upcoming season.