Take a heap of lavender, add a bit of petitgrain and for the base, some benzoin and a touch of civet or some such.
No, it's not as easy. At the very beginning, the citruses are more complicated than just petitgrain - my guess is grapefruit, lemon and maybe even touch of lime. There are definite woody undertones, maybe a touch of sandalwood and that buttery something which is for certain benzoin may also contain a bit of tuberose. I guess that without the huge bucket of lavender, it may be a decent fragrance on its own.
But... well, go and sniff Penhaligon's Lavandula. Great soliflor. Or check the lavender essential oil you have in your bathroom. That's lavender. (Yes, I'm being Captain Obvious. It's to increase the suspense and to underline my nearly-genial thoughts. Now leave me alone, you damn nitpicker there.) Or your grandma's soap. But for Lavandula, I can't remember a lavender fragrance which wouldn't be a room freshener. Lavender is used frequently as a component in perfumery and cosmetics but it is hardly ever given a prominent place. Alas.
Now, La Vallée Bleue is lavender revisited and lifted to another level. The only place I've been to where lavender grows in the wild was the isle of Hvar and I don't remember how that place smelled, it was umpteen years ago and a few more, but the idea conveyed by La Vallée Bleue is close. A lavender-grown landscape.
I've always loved lavender. The smell, the taste, the colour of the blossoms. There is something cooling about them, which is happily absent from the essential oil. Now I got a rendering of live lavender...
... and it was launched in 1943, discontinued some time later.