My overall feeling is, they should return to High Street brands rather than sticking with the same, low quality, high priced food.
I know at first this sounds ridiculous, but even getting places like Nando's, Frankie & Benny's and TGI's into the mix would bring up the amount of people eating in the park. If you consider it this way, if you have more brands people like, they won't bring anything with them, so they will obviously be buying drinks, snacks and things like that in the park, which still provides Towers with money but at the same time, people are eating at places which they know and like. Nando's service is very quick and cheap, you can spend £10 or even less in there and get a meal with unlimited drinks. The other 2 are quite pricey but people would be willing to pay if they trust and know the providers of the food. I'd much rather pay more money to know I'm getting something with higher quality with a high street brand than the own-branded food at Towers.
And then, if they chuck in McDonald's or KFC, people would no doubt be coming with the intentions to eat at the park's outlets, rather than bringing own food because people know the quality and price are both not reasonable.
Even if they trial it, for 1 or 2 years, at Thorpe Park or somewhere like that, do some surveys of what people prefer and the types of food oulets people enjoy going to, before they fully make a go of it, would be a start.
This is just my opinion anyway, I'm all for bringing back the old high street outlets, but mixing in some new ones like Nando's and the table service outlets.