There may have been a breakthrough in the disappearance of Gold Coast teacher Marion Barter.

The 51-year-old went missing after she left for a trip to the United Kingdom in 1997.

7NEWS’ new investigative podcast series The Lady Vanishes aims to help uncover what happened to her.

Mrs Barter was removed from the Missing Person’s Register because detectives believed she went missing of her own volition.

Sally Leydon has led the fight to find out what happened to her mother and has told Chris Smith her absence still affects her.

“This Sunday is actually the anniversary of when she left to go on that year-long holiday.

“It’s always pretty heartwrenching for me because I miss her.

“It’s my sons birthday today and his grandmother’s nowhere to be found, like we don’t know where she is or if she’s okay.”

She tells Chris about her visit to Luxembourg and the possible breakthrough in her mother’s disappearance.

Click PLAY to hear the full interview