Letts and GL/Nfer have come up with a system to test the ability of parents. The nature of the test is to put old tests in new covers and new tests in old covers and only one of the tests are produced by Nfer.
Until the beginning of 2010 the NFER GL-Assessment was distributed through Letts Educational (using the card wallets with designs such as giraffes, fishes etc).
NFER GL-Assessment papers are now distributed by GL-Assessment directly with their own new design covers and new ISBN numbers.
In the mean time Letts Educational have created their own new set of papers. They have chosen to use to original card wallet designs with the giraffes, fishes etc to distribute their own papers.
The way to tell these two sets of papers apart is to look at the bottom left hand side of the cover; if it says GL-Assessment then the contents is original NFER, otherwise it is new Letts own contents.