British police have re-opened their investigations into the disappearance of a teenage Irish immigrant – 54 years after she went missing.

Mary Flanagan was just 16 when she left her east London home in 1959 to go to work and on to a New Year’s party with her Irish boyfriend Tom McGinty.

Officers have now renewed their appeals for information in the oldest missing person case on their files.

The Irish Times reports that her sister Brenda, who was eight at the time Mary disappeared, is convinced she is still alive.

Brendan believes Mary may have eloped with her boyfriend who worked with the merchant navy as a stoker, shovelling the coal into the steam engine fires.

Described in the report as ‘bright and friendly’, Mary was 5ft 2in tall and of medium build with hazel eyes. She had dark, wavy hair and a tanned complexion when she was last seen.

Detective chief inspector Dave Rock told the paper: “The key to this is finding Tom, if he is still alive.”

British Merchant Navy records and birth certificate data show no record of a Tom McGinty however and Mary’s family are now unsure if his surname as something similar like McGuinness or McEntee.

Inspector Rock added: “We understand her father introduced him to her, so he did exist, it’s just his surname that’s a problem.

“We believe he was in his early twenties. I spoke to her brother and he is pretty sure the relationship was a genuine one. He was boyfriend or fiancé.”

Rock, who described Mary’s case as a ‘complete one-off, decided to reopen the inquiry as Mary would have have been 70 in June.

He said: “Rather than just leaving it there letting it run, we decided to reopen it and we’ve opened a number of lines of inquiry.

“I visited the family on Friday and when you meet them you realise this has dominated their lives.”

He also revealed that the family hope that publicity in Ireland might raise some fresh clues as to the boyfriend’s origins and might trigger memories in Ireland where Mary could have surviving cousins on her father’s side whose family came from Pass, Co Westmeath.

Mary’s sister Brenda said the family have never given up looking and is appealing to anyone who emigrated to England to work in the navy in the 1950s to jog their memories about a man fitting Tom’s description.

Brenda said: “She slept in on the day she went missing. She had had a row with Tom and she was really, really upset because he had told her a lie.

“He had told her the lady that he was living with was his landlady but then admitted it was his mum. She was crying and distressed.

“She left for work at 1pm and she never came home ... when my dad went to the factory to see if she had turned up for work, he was really shocked because she said she hadn’t been in work for two weeks.

“She mightn’t want to be in touch with us because she fears rejection, but we need her to know that she won’t be rejected. We still hope to find her. If you don’t have hope you don’t have anything.”

Anyone with information about Mary or Tom’s whereabouts is asked to call the Newham Police Missing Persons Unit in the UK on +44 208 217 5728.

British police have re-opened their investigations into the case of Irish teenager Mary Flanagan, who went missing over 50 years ago.