Mary Jane Hebden was baptised on 11 December 1816, at Pateley Bridge, Yorkshire, England, the eldest child of Mary and William Hebden. Her father was, by family tradition, the squire of the village of Dacre Banks, in the West Riding of Yorkshire. In September 1839, describing herself as a governess, she applied to emigrate under the New Zealand Company scheme. Before her departure she secured future employment as a domestic servant in Wellington. She arrived in Wellington on the Duke of Roxburgh in February 1840. It is possible that she was following her fiancé, George White Bennett, a seed merchant, who arrived in Wellington on the Cuba in January 1840. They were married on 20 November 1840 at St Paul's Anglican Church. Fanny, the first of their five children, was born on 21 January 1842.
In the 1840s George Bennett farmed at Lowry Bay and worked as a clerk in Wellington. In 1852 he was appointed the first keeper of the light at Pencarrow Head, at the entrance to Wellington Harbour. At that time there was no lighthouse; merely a beacon in a cottage. In a letter of complaint he vividly described the conditions the family lived under: 'The House is neither wind or water proof. The stove is of very little use. I have been four days without been able to boil the kettle inside or out. Water is a full quarter mile off. Wood from one to three miles. Lamps and windows to clean every morning besides the former to trim every two howers at night.' The authorities refused to make improvements to the building and it is not surprising that a 2½-year-old daughter, Eliza, died on 6 December 1852.
The harsh conditions of life for the Bennett family at this time were also recorded in the reminiscences of a contemporary traveller, C. R. Carter, who wrote of his visit to Pencarrow in 1853: 'The light-house keeper…with his wife and three children (running about like wild goats), and the lighthouse apparatus, were all stored away in two little rooms, each about ten foot square, and without a fire place. The interior…was accessible to wind and rain on all sides, and in heavy gales it rocked and shook so much as to frighten the keeper and his family out of it, who in that case, took refuge in a sort of cave or cabin, which he had scooped out of the side of the hill'.
Early in June 1855 George Bennett drowned when washed overboard on a boat trip across the harbour. Although there is no official record, it appears that Mary Jane Bennett took over the light-keeping duties. Her last child, William Hebden Bennett, was born six months later in December 1855. After much official delay a proper lighthouse was erected at Pencarrow and opened on 1 January 1859. On 10 January 1859 Mary Jane Bennett became the first keeper of a permanent lighthouse in New Zealand, and the only woman to hold the position of lighthouse keeper. Her appointment was announced in the New Zealand Gazette and she was informed in writing that her salary was £125 per annum, inclusive of firewood.
Well-written letters from her requesting lighthouse equipment and supplies, and replies from the Wellington provincial authorities congratulating her on the correctness of her monthly reports, confirm that Mary Jane Bennett carried out her duties very capably. Although some evidence of difficulties is contained in a letter from the assistant keeper, William Lyall, who wrote in 1860 that 'I cannot undertake another Winter with the help of a woman only', in 1864 marine board officials reported that 'the lighthouse keepers Mrs Bennett and Mr Lyall have apparently conducted their duties in an orderly and efficient manner.'
Family sources say that Mary Jane Bennett returned to England for the sake of her children's education when her youngest son was 10 years old. After 1865 there is no further record of her as lighthouse keeper. She died at Dacre Banks on 6 July 1885. There is evidence that her position as the country's only woman lighthouse keeper received recognition. Her youngest son returned to New Zealand and became assistant keeper at Pencarrow in 1880. The entry for him in the lighthouse keeper's service book states simply, 'William Hebden Bennett Son of Mrs Bennett'.