Jaideep Singh thought his day was off to a rocky start when he missed the train on Monday morning.
That's until he realised the next one that came along counted the Australian prime minister among its passengers.
"I was looking there and said 'That man looks very familiar'," the 29-year-old said.
"So it ended up we are lucky to see the prime minister - we were really surprised."
Mr Singh was headed to the Blue Mountains with his wife to show his brother-in-law the sights while he visits from India.
Bumping into the prime minister on a train isn't something that would happen in India, he told Malcolm Turnbull.
"So Mr Modi doesn't get the train very often?" Mr Turnbull replied, referring to his Indian counterpart Narendra Modi.
"Well, I get the train all the time, it's the best way to get around."
Mr Turnbull spent his journey to Emu Plains in Sydney's west spruiking the benefits of public transport as he went about meeting and greeting passengers and posing for photos with them.
It was a good way to make new friends and bump into old ones, he said.
Moments later, Mr Turnbull met a man called Tony Lewis, who happens to be an old friend of a British spy Mr Turnbull defended 30 years ago.
As a young lawyer Mr Turnbull became a household name with the Spycatcher case in which he defeated the British establishment's attempts to ban the memoir of former MI5 agent Peter Wright.
"That is amazing - that is why everyone should get the train, because we never would have met each other," Mr Turnbull said.
