She had often remained on the London Underground platform at Embankment station just to hear her late husband remind passengers to 'Mind the gap'.

But Margaret McCollum was left upset in 2012 when Oswald Laurence's voice was removed from the station - his last posting - in favour of a digitised announcement.

So she asked Transport for London to reinstate his voice - which they did in 2013 and sent her a CD recording - and it is still played on the Northern Line platform today.

Margaret McCollum can still listen to her late husband Oswald Laurence's voice at Embankment station on the London Underground where his 'Mind the gap' recording is played

Dr McCollum is pictured with her late husband Mr Laurence at their wedding in October 2003

The story has come to light again over the past week after a Twitter thread about it on December 11 went viral, with 23,000 retweets and 44,000 likes by today.

Speaking to the Daily Mail in March 2013, Dr McCollum, who lives in North London, said: 'He was never very far away in my head and in my heart.

'And knowing that I could go and listen to his voice was simply wonderful. It was a great comfort. I would go and sit on the platform.

'(I would) sometimes miss a couple of trains just so I could hear it. Although he could do accents, it was his natural speaking voice - clear, precise, authoritative.

'His announcement didn't say 'please' - it was perfectly minimalist. So that was what I would do, right up until November 2012, until one day, I heard a different voice.'

Dr McCollum has previously told how it is a 'great comfort' to hear her husband's voice again

The announcement first aired in the late 1950s but few knew who Mr Laurence was or what he looked like until the Mail tracked down Dr McCollum in March 2013.

She said she used to visit the northbound Northern Line platform at Embankment to hear the voice of her late husband, with whom she was with for 15 years.

But when the announcement was removed in November 2012, she wrote to TfL to ask for a recording of the announcement, which they sent her just before Christmas.

Then it emerged TfL planned to reinstate Mr Laurence, and he was revealed as a wartime evacuee who joined the Royal Academy of Dramatic Art at the age of 17.

The actor had roles in films including 1956 comedy Three Men In A Boat, 1967 movie The Dirty Dozen, and TV episodes of The Saint, starring Roger Moore.

Dr McCollum asked Transport for London officials to reinstate his voice, which they did in 2013

Mr Laurence is pictured on stage in the early 1960s in his mid-30s (left) and the 1950s (right)

Dr McCollum, who spent 39 years in the health service, regularly commuted by Tube from her home, as did her future husband, but they did not meet until 1992.

It was then that she was flying out of London Heathrow on a guided tour holiday - with Mr Laurence as tour guide, and told of hearing his 'most gorgeous voice'.

They later became partners and married in 2003 after more than 11 years together, but Mr Laurence lost his battle against long term cardio-vascular problems in 2007.

Speaking about his later years, Dr McCollum said in 2013 aged 65: 'I always knew that even when he was gone, I could go and listen to him whenever I wanted.'

TfL have confirmed that Mr Lawrence's announcement is still played at Embankment, although station staff said they had not seen Dr McCollum visit for a couple of years.