No, you're mixing up two separate things. You're thinking of the extra bug in their Imperial Stout which is not Dekkera (another name for Brett) but Debaryomyces hansenii, a different wild yeast that is normally associated with brackish water - which would fit with Lewes being on an estuary.
The phenolics in their other beers comes from a saison-type Saccharomyces in the multistrain used for primary fermentation, which is way more common in British beers than US yeast labs would have you believe, for instance around 40-50% of the main Brewlab strains mention phenolics in their descriptions. The saison yeasts seem to be particularly associated with Yorkshire Squares, and of course Harvey's yeast originally came from John Smith's.