May McAllister was born in Cambuslang the sixth of the eleven surviving children of James McAllister, steel worker and his wife Mary Jane Hannah.

In the 1911 census her mother was the head of the household, her father was presumably working away from home. The family of ten were living in three rooms at 41 Park Street, Cambuslang.

May married steelworker Henry Donoghue on 19 February 1916, when she was 17. Their son Henry was born on 25 July, three weeks after her 18th birthday. Their second son, James was born prematurely in June 1917, but lived for only 23 hours. Their third son, John, was also born prematurely, in May 1918 and lived for two weeks. Their fourth and last child, Mabel, was born in May 1920, and lived for eleven days.

They had separated prior to 1928, although their divorce was not finalised until 1945.

On 26 August 1928, May Donoghue travelled to Paisley with a friend. There her friend ordered an ice cream float for her. Some ginger beer from an opaque glass bottle was poured over her dish of ice cream, and she ate it. When she poured the remainder of the bottle, a decomposing snail slid out.

May Donoghue became ill as a result of having drunk the ginger beer.She sued the manufacturer of the ginger beer, Mr Stevenson. However, as the ginger beer had been paid for by her friend, Mr Stevenson claimed that legally he had no "duty of care" to her.

Mrs Donoghue then embarked on a legal battle which went all the way to the House of Lords. Her victory laid the foundation of modern consumer law. The whole process took four years.

May Donoghue eventually received £200 in compensation.