Guest Jan - I have just been reading the thread about Singing Together, and saw your posting about the Swiss song you were trying to recall. It wasn't The Appenzoller Song by any chance, was it? My earliest recall of exposure to yodelling is probably this song, c 1976-77, but I understand that Singing Together had some 'favourites' that would crop up repeatedly over the years.
The Lincolnshire Poacher was one of my particular favourites