LONDON – Anyone who has ever taken the London Underground (or the bus, train, or pretty much any other form of public transport anywhere) is likely to have witnessed at least one confrontation between strangers.

See also: This mysterious poem is cheering up London

Sometimes it's people stepping on each other's shoes, occasionally it's a misplaced bag, and sometimes – as with the story Scott Sparrow shared on his Facebook page on Monday – it's a case of random rudeness that gets handled swiftly and heroically by a stranger.

Image: Facebook Scott Sparrow

Sparrow's story has been shared over 4,500 times in two days on Facebook. It's also made it to Twitter, where people have been sharing what they think about it.

This is the best thing I've seen on FB in a long time. pic.twitter.com/RBkCInwuVE — Jamie Klingler (@jamieklingler) August 10, 2015

@jamieklingler @bickypeg She is my new role model! Hope I have her spirit when that old :-) — Angi Mansi (@WorkPsychol) August 10, 2015

Great work, anonymous elderly lady!

Bonus: it seems that Sparrow's London Underground-themed stories are a regular thing on his Facebook page, so here's another (albeit slightly different) tale from the tube...

Image: Facebook Scott Sparrow

Sparrow has not immediately responded to Mashable's request for comment.

BONUS: Eerie drone timelapse takes you soaring through London's underground tunnels