Harrison-Bentzen, a student at the University of Central Lancashire, had lost her bank card and did not have cash. The man, who is named Robbie, offered her three pounds--the equivalent of about $4.73 in the United States--so she would have a safe cab ride home.
As Harrison-Bentzen explains on her fundraising page, she found another way home, but she couldn't shake the need to do something for Robbie in return.
What she found out about Robbie next makes the story even more heartwarming.
She wrote, "So I set on a mission to find this man, the more I spoke about him the more kind gestures I learnt about such as him returning wallets untouched to pedestrians and offering his scarf to keep people warm."
Harrison-Bentzen started a fundraising campaign, "Help Robbie, Preston's Homeless Hero," complete with Twitter and Facebook pages. She hopes to raise enough money to fund housing for Robbie.
According to Blog Preston, Harrison-Bentzen is studying fashion and is a Miss Preston 2015 contestant.
In a week, the campaign has raised more than $15,000, and counting.
On Tuesday, she is spending 24 hours outside to raise awareness for the campaign, which ends Wednesday night.
Member of the community have come out to support her, bringing gifts for Robbie and supplies for Harrison-Bentzen and those joining her.
As Harrison-Bentzen does her "sleep out," the campaign continues to gain support online.
@Help_Robbie I think what your doing is truly amazing. More people need to get involved. Xxx— Miss Wright (@twright663) December 16, 2014
WE HAVE REACHED £10k I AM SPEECHLESS!!!!! Thank you so much!!! 😭😭😭💙💙💙— Help Robbie Preston (@Help_Robbie) December 16, 2014
With so much bad stuff going on in the world it's great to read about this. Every1 have a look and get involved with @Help_Robbie— Anthony (@TonyPearson1971) December 16, 2014
Before the "sleep out," Harrison-Bentzen posted a message on the Facebook page to thank Robbie's supporters.
"I am literally amazed that this all started just under 1 week ago and together we have exceeded not 1, not 2 but 5 targets! Unbelievable," she wrote.
She said she is doing it because she hopes these little acts of kindness will add up to spread some big Christmas cheer.
Click here to visit the "Help Robbie" fundraising page.
Photos courtesy of Blog Preston used with permission