Hi all, and welcome glasshypo.
Sydney and I have tried to research this question and I think we can only clarify the question by referring to the literature.
There are three books which seem to agree exactly on what is 'Carex'.
They are credited here and the photograph is copyright of the named publisher. (Sorry I can't manage better copies of the images at this moment)
The first image comes from the 1937 Leerdam catalogue which shows the 'Carex' and 'Robur'.
http://www.hogelandshoeve.nl/gmb/carex%201937.jpgI've tried to enlarge the photo of 'Carex' for a clearer view.
http://www.hogelandshoeve.nl/gmb/carex%201937b.jpgThe second image appears in 'Modern Glass in Nederland' by Titus Eliens. (Waanders/Gemeentemuseum Den Haag,2002 ISBN 9040086710)
http://www.hogelandshoeve.nl/gmb/carex%20te.jpgThe author also states '..the Carex drinks service, described in the company's designer glass catalogue of 1935/36 as a service for everyday use, 'which is able to withstand a knock or two'. The service derives it's name from the square cut glass foot supporting the egg-shaped bowl of the glass. The design of the foot is odd to say the least, because the shape suggests the use of a press-moulding technique. Copier is said to have been inspired to produce the design, which is not at all typical of his functional design philosophy, by a similar squarefooted glass created by the French Art Deco designer Jean Luce (1895-1964)'
This image is also reprinted in 'AD Copier & Lino Tagliapietra; Inspiration in Glass (Gemeente Museum Den Haag /Snoeck-Ducaju, 2000, ISBN 9 789053 493236)
There is a third image which clearly reflects the same service. Originally printed in 'AD Copier-Glasontwerper'by Reino Liefkes (Waanders/Prins Berhardfonds, 2002 ISBN 90-400-9602-3)
http://www.hogelandshoeve.nl/gmb/carex%20rl.JPGI think we will all probably agree that these images are NOT the design which Sydney wants to have identified.
But then we discover that there IS a picture which (IMHO) showns Sydney's glass.
It appears on page 110 of the "Leerdam bible"; 'Leerdam Glass 1878-2003' by Annet van der Kley-Blekxtoon.
http://www.hogelandshoeve.nl/gmb/carex%20akb.jpgThere it is!!
On the extreme left, and clearly identified as Carex. (??)
Actually if you look carefully that last glass looks kinda out of place, the foot is disproportionately thicker and the rim is clearly flared (rather than the 'egg-shaped' bowl referred to and seen above).
Is it possible that there is a mis-identification in the standard reference work? Could the former director of the National Glass Museum have made a mistake?
I must say that on reflection I am inclined to think that this must be the case.
Obviously it remains a possibility that Sydney's glasses are from Leerdam and even from Copier, but the pattern name probably isn't Carex.
There is no reference to another sqaurefooted service in my Leerdam literature. (But then the literature is not always complete or correct)
I guess we need to ask what the design by Jean Luce looked like (Can anybody help??)