How do breweries come up with their own yeast strands? I know Rogue came up with the "Pacman" yeast strand and Guiness has their own under lock and key.
I may be totally wrong, but I'm under the impression most commercial breweries use commercially available strains, or have trained a specific strain in their brew house to develop a house strain. Some of those 'house strains', like Rogue's Pacman, are available seasonally. Others, like wyeast London ESB (reported to be fuller's house strain) are available year round.
Not sure if that's what you were asking, but hope it helps.