If you're a Londoner, chances are you hear the 'mind the gap' message at least a few times a day on the daily commute.
But have you ever noticed that the voice sounds different at Embankment Station? Let's face it, probably not – but you might do after finding out the heartbreaking reason for it.
Whether you live in the UK capital or not, this emotional story is bound to get those tear ducts working overtime.
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A few years back, historian and journalist John Bull decided to shine light on the story in a series of tweets, in which he described it as a tale of 'London, trains, love and loss, and how small acts of kindness matter'.
It all started just before Christmas 2012, when staff at Embankment tube station were approached by a woman who was 'very upset'.
John wrote, "She kept asking them where the voice had gone. They weren't sure what she meant," but she explained, "The man who says 'Mind the Gap'."
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The staff said not to worry – the announcement voice had simply been updated with a 'new digital system' to offer different voices and 'more variety'.
However, still appearing upset, she said that the voice held a special significance to her – it belonged to her late husband.
"The woman, a GP called Dr Margaret McCollum, explained that her husband was an actor called Oswald Laurence," wrote John.
"Oswald had never become famous, but he HAD been the chap who had recorded all the Northern Line announcements back in the seventies.
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"And Oswald had died in 2007."
The loss had 'left a hole in Margaret's heart', but one thing that brought her comfort was getting to hear him ever day on her way to work.
John continued: "Sometimes, when it hurt too much, she explained, she'd just sit on the platform at Embankment and listen to the announcements for a bit longer."
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This had been her routine for five years, and though it didn't bring him back, it kept his memory alive.
I'm not crying, you're crying.
Although the staff said they couldn't do anything to change it back, they apologised and promised to see if they could find a copy of the recording for Margaret.
But the story doesn't end there.
As explained by the historian: "In the New Year, Margaret McCollum sat on Embankment Station, on her way to work.
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"And over the speakers she heard a familiar voice. The voice of a man she had loved so much, and never thought she'd hear again.
"'Mind the Gap' said Oswald Laurence."
Turns out, a lot of people at Embankment and within the London Underground and TFL services had lost loved ones and wished they could hear them again.
They realised that with these unique circumstances they could make it happen for Margaret.
And so after wading through archives and restoring old tapes while others worked through the code of the announcement system and sorted paper work, they were able to make Oswald talk again.
As well as the restoration in 2013, Margaret was given a copy of the recording to that she could listen and take comfort from it whenever she needed.
Speaking to the BBC, London Underground director Nigel Holness said at the time: "Transport for London were approached by the widow of Oswald Laurence to see whether she could get a copy of the iconic 'mind the gap' announcement her husband made over 40 years ago.
"We were very touched by her story, so staff tracked down the recording and not only were they able to get a copy of the announcement on CD for her to keep but are also working to restore the announcement at Embankment station."
Though the story is nearly 10 years old, much like Oswald's voice, it is kept alive by those who are moved by its emotional significance.