At village concerts in the 1950's there was always a "whistler" a remember "Wee Geordie Campbell", who was only a few years older than myself, but a firm favourite. He whistled pipe tunes, marches usually, with a couple of reels occasionally. As Andy and Gordon have said hearing people whistling at work or when walking used to be common, now we seem to have an inbuilt depression about life.
I whistle very often from the roof tops....sometimes the birds come and join in......the feathered variety of course.