There ARE tigers at London already. So quite how we're going to see a big upturn in visitor numbers through a new tiger exhibit is a bit of a puzzle to me, especially as logically tigers will become harder to see in bigger enclosures.
I believe there will be an maintaining or upturn in visitor numbers as a result of a new Tiger exhibit. Firstly there's more publicity and more people will be tipped into visiting through curiosity and a raised profile. More important for a modern capital city zoo is the "wow" factor which creates word of mouth and even more importantly prevents bad word of mouth -I've heard so many people say something along the line of, "the zoos looking nice but the Lion/Tiger enclosures look a bit crappy". These people were Joe Public, casual visitors who really do pay for the zoos existence, not enthusiasts like ourselves. These visitors don't really have an idea about whether the enclosure is suitable for an animal's husbandry but if it looks nice/spectacular they think it's suitable and will be left with a good impression.
As sooty certainly knows, the fall in visitor numbers that London experienced from the mid 1970s to 1990 has no parallel amongst zoos sited in major European zoos, and it mirrors the slow contraction of the collection in that time
I don't know if you're linking the decline in species kept with falling visitor numbers, but I think you'd be wrong to do so. I think the reality is that people in the UK were visiting pretty much all zoos less during this period (as evidenced by the large number of zoos that closed over the timescale mentioned). This was probably due to a number of factors, the anti-zoo lobby probably had some impact, and leisure options for families became far more varied and easily affordable (theme parks, video films, video games, cheap foreign travel, etc.). In any sector it's often the case that larger organisations struggle to readjust to changes more than smaller ones, so it's no surprise that the biggest struggled most. I believe the average zoo visitor wants to see the ABC animals displayed well and really doesn't get excited over, say, a Cloud Rat like I would.
The fact that visitor numbers are still not back to the 1990 level shows that visitors are not sufficiently attracted to a zoo that still charges a lot of money (nearly £70 for the conventional 2 adult 2 child family) yet now has fewer mammal species on display than nearby Colchester or Marwell.
No, it shows the public has far, far more things to do with their leisure (especially in London) than they did in 1990. £70 is not much different from a number of other large zoos (which might not be in capital cities) and certainly cheaper,longer lasting or better value than, say, London Aquarium, London Eye or a West-end Show. Again, whilst I dearly love Colchester and Marwell I don't think the public get excited and visit because of Geoffroy's Cats, Cherry-crowned Mangabeys or three species of Zebra as such -they want Lions, Tigers & Bears (Oh My!), Apes, Giraffes, Komodos, and London offers a fair spread of those species.
Personally, I'm just very happy to see London in balance and moving forward rather than standing still and/or stagnating