Looking for the name of this musical movie title..HELP

Dear all ^ ^

This is hard but I will try to describe as much as possible.
This is an old classic musical movie

I really can't remember the names of actors or actresses
All I can say is that;

The movie starts in Modern time (in movie time of 60s or 70s)
I think it was London or somewhere because I remember there was this BIG CLOCK TOWER like BIG BEN ^^
Anyway, 2 Grown ups were in the park (music and song) and then somehow there was this big rain and thunder then an accident occurred. Both got fainted. By the time they woke up they were in Medieval time of England...

They were apart then met again but the King (or the Lord) of that castle somehow thought this guy is an enemy or something so decided to Chop off his head or Burn him or something... (This is best part that I remember) then he realize something about the time of eclipse in the history of England, which happened to be that very own time that he is about to die...

So he plays trick saying that he is angry and he will banish the SUN for ever.
Nobody believes him... so he checks the time eclipse and starts making funny magic spell to banish (LOL) the SUN. The SUN becomes dark, everybody is scared and believe his power. He was released..... ^^

There was this one music that I vaguely recall.... the lyrics of the end of the music goes something like... <.... You and I will be, tu tu tu tu~ IN ~ LOVE ~>

PLEASE, CAN ANYBODY HELP ME ????????????

Please contact me at cyber_oh <at> yahoo.com

THANKS