Not sure I'm convinced by that recipe. OCH is one of the best supermarket beers, despite coming from Greene King, but it's an oddity. The secret sauce is the addition of a small amount (<10%) of the legendary Old 5X, a 12% beer aged in oak vats for 2 years most famously used in the blend for Strong Suffolk. You can taste a hint of the vinous complexity that it brings but it's pretty hard to replicate that in a single gyle - maybe a generous lump of Simpsons DRC or Special B, maybe a bit of oak dangled in the fermenter.
I assume the main beer is just regular Speckled Hen, which is notable for being fermented relatively warm to really drive ester production. Not sure S-33 is the best match, I'd be tempted by BE-256, which should be used a lot more in British styles than it is, it's a British yeast originally.