Just wanted to follow up on this, last I heard Oulton Park are being particular on what year display cars are from (pre 2000 I believe) for this event which rules out portion of the club from being able to attend unfortunately. Don’t ask me how they can have such different approaches for the Gold Cup vs. Donington Historic Festival 
But there has been better progress on a different event at Oulton Park later in July that some members have started to discuss here:
https://forum.mx5oc.co.uk/t/mazda-mania-at-oulton-park/148640