Events prior to the disappearance

Members of her family, discussing her disappearance in 2013, suggested that Flanagan may have eloped with a man she had been seen with frequently in the last few weeks of 1959. He was supposedly another Irish immigrant and may have worked on the merchant navy, although police say they have never been able to trace such a man.^[3] He was called Tom, and undoubtedly existed under one name or another, as her father had introduced him to his daughter; the latter was in his early twenties at that time.

He may have been Mary's fiancé.^[4] Information on him is sparse, however, and he has also been described as being an Irish labourer;^[2] even his surname is uncertain. He is most commonly referred to as McGinty,^[7] although it could also have been McEntee or even McGuinness.^[7]The Merchant Navy had no record of a Tom McGinty working in their service.^[4]

Her family have suggested that she could have been pregnant, and disappeared because of that,^[2] as it would have been "a major thing for a 16-year-old Catholic to tell her parents" according to contemporary social norms.^[6] One of Mary Flanagan's last known interactions with her boyfriend was later reported by her sister Brenda as being a bitter argument. This had been caused by Mary’s discovery that, although McGinty claimed to be living with his landlady, he actually lived with his mother. This lie, said Brenda, had distressed Mary sufficiently to cause her to oversleep on the morning of the 31 December.^[4] This followed an argument, with "raised voices", between Mary, McGinty and Mr Flanagan, following which "Mary went to bed in tears, telling her sisters she planned to end the relationship" with McGinty.^[5]

Case re-opened, 2013

Police continued to check the National Insurance database, in 1983 and in subsequent years, but reported that her number has never been used for employment purposes since.^[2] In 2013, on her seventieth birthday, the Metropolitan Police and^[2] the local Missing Persons Unit in Newham re-opened her case for examination. The investigating officer described the case as a "complete one-off," and it has been used as an example of the changes that policing methods have undergone over subsequent years:^[3] from knocking on doors in the community in 1960s, to accessing Facebook profiles in the 2000s.^[2] Police particularly appealed for information on Tom McGinty.^[8] In January 2017, the charity Missing People commissioned a new age progressed image of Mary from UK forensic artist Tim Widden.^{[1][note 2]}