Dating lingerie help please

I bought this lovely lingerie set from a second hand stall at a village féte a couple of years ago but am not quite sure of its age - I'm leaning towards 1940s.
Pretty sure it's silk and very beautifully handmade. The full length slip has a metal side zip. I have spent ages searching online but can't find quite the same style of knickers/ shorts anywhere. The ribbon straps are quite fragile and have broken on one side of the slip. There are a few age related/ storage marks - I have kept it wrapped in acid free tissue paper in a cardboard box. I think it is so beautiful and it feels really soft and sensuous to the touch - maybe it was made as a wedding set as part of a trousseau? I have attached some pictures (sorry - there are quite a few!).
I'd be very grateful for any ideas regarding it's age. Also - would the lace be Chantilly?

 

Lovely! I would say 1930s on that set.

 

Gosh, just wonderful! At a guess I would have said 30s-40s but you already have some expert advice so i shall go to the back of the classroom and take more notes

 

Thanks to everyone for your replies.
Seems that it's slightly older than I first thought - it's in such good condition (apart from the slip ribbon straps) for its age. I don't think it has ever been worn or washed.
It was folded up in a plastic carrier bag with a lot of vintage doilies and hankies - needless to say I bought the whole lot!

 

It is a gorgeous set, and to have them all together is wonderful. It looks like it is the very fine hand made French lingerie that used to be made before WWII. The lace looks hand made as well. As you suggested, it may be a trousseau. I have never seen an entire set kept together like that, unworn. A treasure!

 

Definitely 30's. Beautiful!

 

The set may be even a little earlier. This is from my 1920s magazine.
A beautiful set.

 

I would not think to find a zipper in lingerie in the 1920s.

 

I was thinking the zipper may have been added by the owner. The bandeau bra looks 1920s.

 

I have just had a good look at the zip - it has no markings at all.
I did wonder if the zip had been added at a later date but looking again at the way it fits in to the seam and the way the fabric has been cut would suggest to me that is original to the garment. But I could be wrong!

 

The stitching around the zipper seam doesn't appear to be well done, but that could just be my screen.
This is why I thought it may have been added.
Any which way, it is a gorgeous set.

 

Could you turn it inside out and take another picture of the zipper? That may help

 

Here are some pictures of the zip from the inside. I am now beginning to think that it was a later addition - the zip just seems a bit clunky for such delicate fabric.
G oodness knows ho w anyone could have put it on with or without a zip - they must have been teeny-tiny!
The slip wouldn't go over my mannequin so I had to pin it on the front to take the photos.

 

Don't know what happened there - there are only 3 pics but they seem to have been duplicated!