The fifth oldest zoo in the world unveiled previously-unseen artefacts and old footage yesterday as it marks its 175th anniversary.

Bristol Zoo Gardens first opened its doors in July 1836 and since then has welcomed six generations of visitors, helped to save more than 175 species from extinction and given more than 90 million visitors a great day out.

The zoo’s archive room has been opened up to the media to reveal photographs, signs, records and films that have not been seen in decades.

Don Packham, 78, who worked at the zoo for 50 years before retiring as head keeper in 1998, described the pleasure that working with animals had brought him.

“It was a great privilege to work with many of the animals we had here, the rhinos, the polar bears, the elephants,” he said.

“Being part of that, only a very small cog in the wheel if you like, but being part of it was a wonderful privilege.”

Among the zoo’s more famous animals were Roger, a rare black rhino, the first ever born in the UK in 1958, and Alfred the gorilla, who lived at the zoo from 1930 to 1948 and at the time was the only gorilla in captivity in the country.

But many people remember Bristol Zoo’s elephants – Zebi the Asian elephant, who arrived in 1868 and became known for removing and eating straw hats, and Rosie who gave rides to children in the 1940s and 50s.

During the 1960s elephants Wendy and Christina were known for being taken for walks to Whiteladies Road.

“First of all we started walking them around the zoo until they became lead-trained. They weren’t on a lead, but we used to put a collar around their necks so we could hold on to them if we needed to,” Mr Packham said.

“Once we did that we started going further afield and we took them around Clifton, usually on a fairly regulated walk, the same each day.

“This was good for the public as they knew where they were going to be at roughly the right time, so they would come out of their houses to offer them some food of some kind.

“This went on for a very long time, I forget exactly how long, but I do remember the occasion that they stopped it.

“We were walking down one of the roads off Pembroke Road, which is the main road leading down from the zoo, and a little Pekingese dog came running out of a house and yapping as these dogs do, and this dog frightened Wendy, the elephant, and she bolted.

“She ran down to the end of the road and straight across the main road.

“By pure good fortune there was nothing coming, no-one on the pavement, no cyclists or motorbikes or anything like that and she got across to the other side perfectly safely.

“We were able to get her back and bring her back to the zoo, but after that we decided it was too risky to continue.

“The walks were contained within the zoo after that and they were still taken out several times a day and they enjoyed that just as much.”

Mr Packham, who grew up in County Durham, moved to Bristol to start work aged 16 as a junior keeper, having applied for a job at every zoo in the country.

Describing when he first started at the zoo, Mr Packham said it was very much about the grand day out.

Zoo historian Tim Brown, who has been researching Bristol Zoo for many years, said: “When the zoo opened it must have caused a sensation.

“It was looking toward the newly enabled middle classes in Bristol – the people who had been recently educated and who had money to be the patrons of this zoo.

“We must not forget that in 1836 there were no photographs, there were drawings of animals in books, some of which were wildly inaccurate, so to see lions, tigers, leopards, monkeys and all the birds that came here must have created an absolute sensation.

“One could imagine that the people who couldn’t afford to come to the zoo must have looked at this place with some envy and fascin-ation.”

Many of the photographs, film footage, signage and records in the zoo’s archive room have been in storage and are unlikely to have ever been seen by the public before.

“Here we are in the archive, surrounded by artefacts of the past. As much as anything here I like the old admission signs that remind me of a time long before I was born when things were a great deal more innocent.”

A new book about the history of Bristol Zoo will be going on sale to commemorate its 175th anniversary.

Zoo director Dr Bryan Carroll said: “There’s a certain responsibility of history, and with it being the 175th year really brings that back to you.”

The archives show the change in social attitudes, with zoos no longer seen as a recreational activity but as a protector of wildlife.

Bristol Zoo will be celebrating the anniversary with a host of events and activities.

The highlight of the anniversary year will come during the summer when the zoo places dozens of colourful, life-size, gorilla sculptures around Bristol in a public art exhibition.