Taylor Swift wore Zimmermann’s Luna corset midi dress for a London date night with Travis Kelce on Thursday. / SplashNews.com Taylor Swift brought a garden party to London’s theater district. The singer and fiancé Travis Kelce hit the town on Thursday to catch Sadie Sink’s West End debut in “Romeo & Juliet” at the Harold Pinter Theatre — and Swift dressed for spring in a Zimmermann Luna corset midi dress ($1,950). She paired the floral number with Jimmy Choo strappy sandals ($950) and a JW Anderson woven top-handle bag ($1,995) in mint green — a color that echoed the palette of her 2025 album, “The Life of a Showgirl.” She kept warm in a black tailored jacket that added a menswear-inspired touch. The couple caught Sadie Sink’s West End debut in “Romeo & Juliet” at the Harold Pinter Theatre. / SplashNews.com Swift’s Larkspur & Hawk Posy tourmaline earrings are inspired by 17th-century English embroidery.…