Holland Park was as low-tech as could be in representing the Alps, the avalanche etc. There was a vast white sheet with guy lines attached at strategic points, so that at a moment's notice the mountains could rear up, a crevasse appear, the avalanche be suggested. Very inventive, I thought, but imagine what Hollywood could achieve these days!
The singing was nowhere close to the quality of Tebaldi, Del Monaco and Cappuccilli, but then I didn't expect it would be.
Have you heard Frances Alda's aria (recorded 1912) from Catalani's Lorelei? Simply wonderful.