I don't think the motivation for any collection to keep pure tiger subspecies should be gate revenue. There is a need for indo-chinese and malayan tiger ex situ management for the sake of maintaining reserves of this species, with the malayan represented in some European collections. I don't think it matters whether a zoo decides to join the Amur tiger EEP to act as a holding for non-breeding animals, or works to bring Malayan tigers into their collection, the point is that they are taking seriously their ability to contribute to captive tiger management. I wouldn't think it for the benefit of the public, let alone the zoo enthusiasts among them, regardless of how keen their subspecific radar might be...
Is there are shortage of space for Amur and Sumatran tigers within the UK and europe? Chester, Howlettts and the Kent Big Cat foundation have all added Sumatran tigers in the last few years. Longleat has switched to Amurs in the last couple of years and Dublin added them alongside the existing sumatrans. Has the recent increase in African lion births in UK safari parks been due to a demand for African lions by zoos, or was it unplanned and put pressure on collections to rehouse their cubs? Someone else mentioned there aren't as many asiatic lions available to collections that would otherwise opt for them, would this be connected to it?
What I get from this, and other threads, is that West Midland Safari Park is causing themselves and now possibly Chester a slight issue through the unethical breeding of mutation cats at levels not seen elsewhere in this country for some time. I can only assume it is extremely profitable for the park to do so. Meanwhile, far from ideal enclosure rotation has to happen at Chester.