Tom Hiddleston has made his relationship with Taylor Swift official. While he hasn't popped the question quite yet, in a nod to modern dating etiquette, he has finally followed her on Instagram.

While Tom didn't waste any time going public with his blossoming romance with the Love Story singer, indulging in PDA's and declaring his love on a T-shirt, fans noted that he hadn't yet followed his girlfriend on social media.

The actor, who is renowned as an old-world romantic, is a recent convert to the social media site and while he earlier posted a photo of himself in character as Marvel's Loki, he hadn't followed anyone - including his girlfriend.

Meanwhile, his Ironman co-star Robert Downey Jr couldn't help but use Hiddleston's arrival on Instagram as an opportunity to poke fun at the British star.

Captioning the now infamous picture of Tom wearing an 'I <3 T.S.' shirt taken over the Fourth of July weekend, alluding to his own character Tony Stark, he wrote on the photo sharing site: "Join me in welcoming the biggest T. Stark fan of them all to Instagram! @twhiddleston (sic)"

Join me in welcoming the biggest T. Stark fan of them all to Instagram! @twhiddleston

A photo posted by Robert Downey Jr. (@robertdowneyjr) on

In an interview with the Los Angeles Times The Night Manager actor said it was all in good humour. "Robert and I are very close and I got to know him working on the Avengers in 2011. There's a lot of mutual affection. I feel like it's an expression of mutual admiration. It's great. He's very sweet.

Taylor has had her fair share of ex's come and go on social media. After his sudden split from the 26-year-old star, Taylor's ex Calvin Harris initially tweeted a message suggesting the break-up was amicable. However, following a Twitter spat, it wasn't longer before the pair unfollowed each other, a sure sign that this former couple were "never ever getting back together."