BTW, I do not know how many units exist and where they all are. But I would say to consider this:
If the UK Food processor growing was being done at the zoo, even if it was grown for all the public to see, how would anyone from the public or even on staff tell the difference between trays containing zoo plants and trays containing trial plants, if they were not told about them?:-)
Anyway, I am not positive how the trials are being done, but something to consider, as I think it would be very easy to hide the trials in plain view:-)