I recently came across this blog post:

http://www.hopshopuk.com/blogindex.php/?p=56

Since Vina, the owner of the Gervin brand, called in the
administrators in March we have been unable to obtain any stocks of
these yeasts.

We have been told repeatedly over the past few months that these
will be available within days but none have arrived as yet.

If they are produced again to the high standards originally set by
Gerry Fowles, which would mean being packed in nitrogen flushed
sachets to ensure both a long shelf life and high viability, we
shall again be stocking the full range.

At the moment we do not know when or if this will be. In the
meantime if we receive orders for strains of Gervin yeast which are
unavailable we will substitute with the nearest equivelant yeast
from the Lalvin range.

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Bob just used 'canonical' in the canonical way. [Guy Steele]