While Matthew Vaughn made one of the best superhero movies in recent memory with the reboot/prequel X-Men: First Class, his time in the X-Men franchise was not supposed to be a one-and-done. After the whirlwind experience of making First Class, Vaughn was signed on to co-write and direct the sequel, which would move the time period to the 1970s and bring the Sentinels into the mix. But deep in development, Vaughn exited the project, Bryan Singer took over, and it became the X-Men: Days of Future Past we know today.

However, Vaughn recently revealed that his original plan for the First Class sequel was to introduce a new young Wolverine character, with the Days of Future Past storyline not coming into play until the third film. Speaking with Uproxx, Vaughn shed some light on his early plans for the First Class follow-up:

“The reason I haven’t done sequels in the past is they just weren’t exciting me. And on Days of Future Past, even though I co-wrote the bloody thing, the reason I bailed out of it is two things: First, I respect Bryan Singer hugely and X-Men is Bryan’s world and I feel he let me play in his sandbox. I enjoyed it, but it wasn’t my sandbox. I wanted my own sandbox. And, second, I didn’t want to do Days of Future Past next. I felt that one should be in a trilogy and Days of Future Past should be the finale of that story. I would have done a film in-between where you meet the young Wolverine and a new character, and then Days of Future Past became the young Wolverine and the old Wolverine and just really blow it out.”

Vaughn goes on to say that the studio didn’t agree with this plan and wanted to make X-Men: Days of Future Past next, which is one of the reasons he left to go make Kingsman: The Secret Service.

Curiously, Vaughn spoke with us in 2014 about his original Days of Future Past plans and said the finished film was “90%” of what he had written before he left the project:

“Bryan [Singer] did a few things, which I thought were genius that weren’t in my script. I had Juggernaut breaking into the Pentagon, he changed it to Quicksilver and did that fucking brilliantly, I have to add. My idea was the sentinels at the end, I wanted them to look like Mystique. I thought there should be thousands of Mystiques attacking them in the future. He changed a few more of the mutants, but it was pretty close. Yeah, it was pretty close.”

So when Vaughn says he wanted to do an in-between movie before Days of Future Past, it sounds like that idea was shot down early in the process and he moved on to co-writing and developing to direct the Days of Future Past storyline. But as Vaughn says, his heart wasn’t really in making Days of Future Past next, and that was one of the factors that contributed to his exit.