My S went through a 2.0m restriction in Wanstead (east London) the other week - slightly helped by the fact that previous collisions had left the posts leaning a bit outwards, but still required me to hop out and guide the driver through with mirrors folded. X would not fit at all!
I wouldn't have gone that way if I had remembered the size correctly; I had thought it to be 2.2m, and I've been happy with others that size in the S.
S is 2287mm over mirrors, 1964mm mirrors folded; X is 2271mm/2070mm. 7' is 2133mm - if it's actually that size, it will be really tight in an X, and I don't think I'd take one through without an assistant.