Help!!

If anyone can get this i will be amazed!!!

I saw this films manys years ago, I think it a 1950 - 1960's film...But i
maybe wrong.

All i can remeber is this

Its set in a City...in a large high rise building. Not sure what the company
did.

The building has a canteen or its a cafe across the road( or it could be the
internal post, confused? i am), which this women works in serving food( or
sorting post). She talking to her friends when this guys walks in...she
looking at him...and he is with other people talking business...

I think she leaves and goes home...

The other part i remeber is later on in the movie the guy is walking across
the floor with his boss (I think) and there is poeple comming out the lift
singing..i think it turn into a musical...he trying to speak to his boss ect
ect...

Its a feel good movie...

I have no idea what the plot of the film is...i think these 2 fall in love
maybe...

Its a film ive been trying to find for too long...


Many thanks in advance

Karl