It's been five years since people were left baffled by a series of very apologetic signs that appeared around Prestwich.
The hand-written posters were stuck to things like traffic lights and lampposts, and read, "I'm so so so sorry."
Unsurprisingly, the question immediately on everyone's lips was, who is this person? And what had they done?
Community Facebook page Original Prestwich People shared a photo of one of the signs on social media.
Immediately, theories behind the reason for the posters began to circulate.
Was it an unfaithful partner?
An apology from someone who went through a red light, or a council member saying sorry for parking or road problems?
Half a decade later, the guesses are still coming.
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Original Prestwich People reshared the post earlier this week, and even now no one seems to be 100% sure what they mean.
Page admins do have a theory though.
They think it could have been the early work of Manchester street artist 'Al Shep', whose artistic snippets of song lyrics can be found across Greater Manchester.
Many are the words of the region's best known bands - Stone Roses, Joy Division, Buzzcocks.
I'm So Sorry was a song by The Smiths, so it's possible the signs were a tribute to Morrissey and co.
But as it stands, this theory too remains unconfirmed, and the mystery of the signs unsolved.
