The only bubble gum-like flavor I've experienced was from Belgian Saison yeast. Is it possible that your temperature measurements were off or that you under-pitched? How were you controlling the temp of the carboy?
My guess is either the fermentation temperatures were higher than you realized or you under-pitched. From what I understand it's usually a flavor produced by Belgian and Bavarian yeast strains so I think it's kind of strange that it happened with an English strain.