I just received this new product from a new ebay seller in England who goes by "britkit06". They are affiliated with a British paratrooper living history group.
Anyway, this 24-hour ration kit looks the most like the real thing, as I recall from photos (rare) I have seen of D-Day examples, at least. The 3 chocolate "slabs" as the Brits call them, and the 2 "biscuit" packs etc. look like great copies of what I remember in photos. The boxes are about the same size as the ones more often available from ebay seller "reprorations" here in Oregon, but I think these kits are more realistic. And their emergency ration tins (cool, and very handy) are the correct size.
British WWII Reproduction Ration
British WWII Reproduction Ration
Rational sent me these pics to post from a new British WWII Reproduction ration. Here's what he had to say about the ration: