Jimmy Chipperfield, born 1912 and died 1990, had spent his life with animals nobody else knew how to handle. His family's circus, Chipperfield's, was one of the great British travelling shows, and Jimmy had grown up training and transporting the kind of creatures most people only saw at the zoo. By the 1960s, the circus business was changing. Public taste was shifting away from caged spectacle. Chipperfield saw something different: animals in space, visitors in cars, the cage flipped inside out. The visitors would be the ones boxed in. The animals would have the open ground. The idea was strange enough that almost no one outside Africa had tried it. The 6th Marquess of Bath, looking for a way to support Longleat House without selling it off piece by piece, listened, and said yes.

The East African Reserve became the heart of the park, sixty acres laid out so that visitors creep through in their cars while Rothschild's giraffes drift between Grant's zebras and black wildebeest. Ostriches stalk past the windows on legs that look engineered for a different planet. South American tapirs nose through the grass next to ring-tailed lemurs. In 2022 the reserve added a male capybara, the world's largest rodent, looking permanently unimpressed by everything around him. The animals are not performers. They are simply there, doing what they would do, while the cars pass through. It is the inversion that still surprises people. The bars belong to the audience.

For decades, the small island in Half Mile Lake belonged to a western lowland gorilla named Nico. He lived alone, with keepers ferrying his food across by boat, and a heated indoor refuge for English winters. When he died on 7 January 2018 at the age of 56, he was one of the oldest gorillas in Europe, the third oldest western lowland gorilla on the continent. The Jungle Cruise still passes the island, though now black-and-white colobus monkeys move through the trees Nico once watched from. The Monkey Temple, opened in 2012, lets marmosets and tamarins run free along rope walkways above visitors' heads, small enough to pass between worlds. In 2019 the koalas arrived from Adelaide, the only southern koalas in Europe, and in 2022 the first southern koala joey ever born on the continent opened its eyes at Longleat.

Long before the lions arrived, the Longleat Railway was already running. Established in 1965 and expanded in 1976, the ridable miniature railway threads through scenic woodland and along the edge of Half Mile Lake. It is among the busiest miniature railways in the country. The first operators were an outside company called Minirail, on a ten-year contract that ended in disagreement; Longleat took over running it themselves in 1976. The fifteen carriages, all built on the estate between 1976 and 2013, wear a mock British Railways crimson and cream livery that would not look out of place on a 1950s mainline platform. Between 2011 and 2017 the line was rebranded the Jungle Express, themed up to match the safari beyond the trees. Now it is just the Longleat Railway again, miniature steam and diesel under tall English oaks, with lions a few minutes' walk away.

The 1967 BBC documentary The Lions of Longleat introduced the country to what Chipperfield and Lord Bath had built. A 55-part series called Lion Country followed in 1998, and since 2000 the BBC's Animal Park has returned to Longleat almost every year. The model spread: drive-through safari parks now exist on every continent that allows them. The original is still here, sixty years on, with the koala joeys and capybaras that nobody imagined in 1966. Longleat House still stands at its heart, the Marquess of Bath still in residence, the lions still indifferent to the cars.