The concept of the Special Relationship was given a boost by Churchill, when he used the expression. But the reality has been that the relationship has often been shaky, both Governments opposing the other on occasion over military action etc.
It is doubtful now that Intelligence sharing will be at the level it used to be, we are a leaky ship in that regard in the U.K, as was the U.S under Trump of course.
Trade links have been all but severed by Johnson and Gang's attitude to N.Ireland. and other things.
All in all, there is still a kind of concept of a Special Relationship, witness Biden's tweet saying so, but the reality is it is a very shaky and weak alliance, the two Nations , particularly now, are nothing like a "Dual World Power" as the org. labels them, and never really were.