Mary Ann Britland (née Hague) was born in 1847 in Bolton, Lancashire, England, as the second eldest daughter of Joseph and Hannah Hague. In 1866, she married Thomas Britland at St Michael's Church in Ashton-under-Lyne. The couple resided at 133 Turner Lane, Ashton-under-Lyne, with their two daughters, Elizabeth Hannah and Susannah. Mary Ann worked as a factory worker during the day and as a barmaid in the evening to support her family. 

In February 1886, Mary Ann purchased "Harrison's Vermin Killer," a poison containing strychnine and arsenic, under the pretense of dealing with a mouse infestation. Her first victim was her 19-year-old daughter, Elizabeth Hannah, who died in March 1886; the death was initially attributed to natural causes, allowing Mary Ann to claim £10 from a life insurance policy. 

Her husband, Thomas Britland, became her second victim, dying on 3 May 1886, with his death misdiagnosed as resulting from epilepsy. Mary Ann collected £20 from his life insurance. Following these deaths, she moved in with her neighbors, Thomas and Mary Dixon. On 14 May 1886, Mary Dixon died under similar sudden and suspicious circumstances. ​

The pattern of unexpected deaths raised suspicions, leading to the exhumation and examination of the bodies, which revealed lethal quantities of poison. Mary Ann was arrested in May 1886 and confessed to the murders, stating she desired to marry Thomas Dixon. She was tried and found guilty on 22 July 1886, and subsequently executed by hanging at Strangeways Prison in Manchester on 9 August 1886, becoming the first woman to be executed at that facility.