By Jozef Hall, BBC News, in Cambridge
A prosthetic limb, mobile phones and sleeping passengers were among the things found by staff checking buses at the end of their runs.
The discoveries were revealed by employees who were talking about the job of cleaning buses.
Two new £60,000 bus washing machines were unveiled at Stagecoach East’s depots in Cambridge and Peterborough – and are capable of cleaning 100 buses an hour.
On a visit to Cambridge, drivers and cleaners gave the BBC an insight into their work.
Sylwia Bajon, 41, is in charge of keeping the buses clean.
“Every night we can wash over 100 buses,” she said. “Each morning, a further 50.”
She said the new machines were more eco-friendly than the old ones.
“These new washers are better in every way. They are much quieter. They are much faster. We love them.
“We now use recycled water only. Around 50-70 litres in total.”
Despite having expensive bus washers for the outside, the inside still needs old-fashioned elbow grease.
Stagecoach said an experienced cleaner could sweep an entire bus in under a minute. However, a deep clean would take one person at least four hours.
Luis Santos, 65, joined Stagecoach 13 years ago. He cleans buses when they arrive back at the depot in the evening.
“What’s the strangest thing I have found left behind? Well, one passenger… he was sleeping under a seat. Completely asleep,” he said.
“I didn’t know whether he was even alive or not. So I gave him a touch. A little touch with the sweep. He was alive.
“He said ‘hello’. Then he go.”
Driver Ahmed Adu, 42, joined Stagecoach two years ago.
“I really enjoy my work, it is fun. And we find a lot of things left behind. Funny, funny things.”
When pressed for details, he said: “Sometimes we find… how you call it? Ladies’ things. Purses. Money, mobile phones. Lots of phones.
“One time, I’m checking the bus… and I find a leg. A false leg.”
Asked if he found littering passengers frustrating, he said: “No. We want our customers to feel free. It’s not their intention to do that. You just need to have patience with them”.