Fred Astaire steals every scene he is in

I just saw this last night and while it is an enjoyable romp, i felt that it kind of lost steam during the second half. The first half is enjoyable enough with Lemmon defending Novak, but the part including just before the court scene going forward seems like an entirely different movie. i am not sure it was really necessary.
Someone suggested earlier that Blake Edwards - later of Pink Panther fame - had a larger hand in the second half. I am a fan of Edwards, but would agree that it seems as if the first half was written by an entirely different person and then the second half was put on to "liven things up."
I am not trying to be too critical, but the whole train & helicopter scenes looked forced.
Fred Astaire on the other hand was great as Lemmon's State Dept Boss who is keeping one eye on Lemmon and one eye on his own career. The scenes where he is dealing directly with Lemmon and Scotland Yard, are gems.
Just watching him march down the hallway on the way to his office in the mornings and his body language was a treat.