The 'Hello' hitmaker and the 'Harry Potter' author spent time with the 'Delicate' singer as she topped off two nights at the London venue, which saw her bring out Robbie Williams for a duet of 'Angels'.
The 28-year-old pop megastar took to Instagram on Monday (25.06.18) to share how ''stoked'' she was to have the 30-year-old singer/songwriter and 52-year-old novelist in her company, and said she was ''grateful'' for the ''worlds'' they've ''created through their art''.
Alongside polaroid selfies with the pair, Taylor captioned the post: ''I'm so grateful for these women, for the words they've written and the worlds they've created through their art.. so stoked to have you at the show in London @adele and JK love. Always [sic]''
Adele's attendance at the show comes after reports she is back in London preparing her next album, which she is hoping to release by Christmas.
The 'Chasing Pavements' singer hasn't dropped any new music since 2015's '25', but it looks like fans could be in for a treat later this year as she's been having meetings with her record label Sony, and is planning to spend the summer writing ballads for her fourth record so that it's ready for the festive season.
A source told The Sun newspaper's Bizarre column: ''She's back in the UK and intends to write here. A number of studio musicians have been approached to work with her and she's already penned some of the songs.''
Her decision to get back in the studio comes just a year after she revealed during her 'Adele Live' tour that she was planning to take an extended break from touring in order to focus on having another baby.
Adele - who already has five-year-old son Angelo with husband Simon Konecki - said at the time: ''I'll see ya later, I'll see ya on the other side. In a couple of years when I'll be back, you won't be able to get rid of me. I'm going to go and have a baby.''
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Sometimes actors are not acting.