Ilha de Queimada Grande is an island found off the shore of Brazil, due south of São Paulo. Refreshingly it is totally untouched by human developers. Why? Well I can not think of a better reason in the world not to visit an island than the fact it has between one and five snakes per square meter.
Of course these are not nonvenomous snakes, like life is ever that easy. These are bad arse killer snakes and include a unique species of pit viper called the golden lancehead. It belongs to a family of snakes responsible for 90% of Brazilian snakebite-related fatalities. On the island these beasts grow to over half a meter long, their powerful fast-acting poison melting the flesh around their bites (nice). In fact they are dangerous that Brazilian Navy has expressly forbidden anyone from landing on the island, with the exception of scientists who will be wearing a LOT of protection.
Maybe the solution to protect London’s greenbelt is to populate the area with snakes, or maybe something a little more visual like lions. You can’t question the fact it would work.