I have been trying to find out what this piece of music is for over a year with no luck.
I recorded myself whistling the tune - most of it is a string orchestra with a quick flurry from a flute at the end. It then repeats.
I think it was from a film but I can’t place it. The overall feel of the piece is very relaxed and happy. Think almost elevator music style.
Here is the link of me whistling it. Apologies for the loud start. https://vocaroo.com/i/s0QsF8moxd8S
EXTRA: I managed to get a violin friend to quickly try and recreate this song. What he recorded is not the right key (the orignal is much happier sounding) but maybe this might give you the gist of it anyway. (This is the string orchestra section). The flute trill part comes after this.