Mary Eleanor Gillham MBE (26 November 1921 – 23 March 2013) was a British naturalist, university lecturer, and writer, who was resident for many years in Gwaelod y Garth and then Radyr, in Cardiff, Wales until her death.

Although born in a London suburb, and serving five wartime years in the Women's Land Army working on multiple farms,[1] Mary Gillham spent much of her time in Wales.

As a post-war student in the University of Wales at Aberystwyth and Bangor, she gained a degree in agriculture, a first-class honours in botany, and a PhD in island ecology.

Spray-washed seabird colonies were her main love, and research on these took her to remote islands in many parts of the world, where she has lived in tents, huts, lighthouses, etc.

Her major research projects were around the coasts of West Wales (her PhD thesis), Australia, New Zealand, and South Africa, and she was one of the first women scientists to join an Antarctic expedition (in 1959/60).

[1] Gillham attended Ealing County School for Girls, where she earned her Clerical Assistant's Grade I in April 1938, which would qualify her to later work at London City Council office in Westminster.

[10] When World War II ended in 1945, as a former member of the Women's Land Army,[11] Gillham was eligible for a grant to go to university; something her family couldn't have afforded in peace-time.

[14] On 1 March 1957, she began a one-year Botany exchange lectureship and wardenship at Massey University, in Palmerston North, New Zealand, where she moved into Moginie House.

She gave her Extramural lectures in a range of locations in Wales, including: Cardiff, Merthyr Tydfil, Abergavenny, Risca, Llwynypia, Pontypridd, Gwaelod-y-Garth, St. Donats, Bargoed, Hay, Bridgend, Barry, Cowbridge, Porthcawl, Bassaleg, and Llantwit Major, mostly on topics of botany and natural history.

Gillham also led numerous study tours for her students in locations closer to home: Guernsey (1969), the Shropshire Hills (1970), Monmouthshire (1970), Skomer Island (1978), Norfolk (1986), the Heritage Coast (1987), Gower (1987), Merthyr Mawr (1988), and Scilly Isles (1988), as well as further afield: Corfu (1969), Sardinia (1985) and Portugal (1986).

[3] Gillham left London by boat on 19 November 1956, arriving at New Zealand on 22 December 1956, after 331⁄2 days of sailing (stopping at Curaçao, Panama and Pitcairn on the way).

[15] She joined a one-week trip to Rotorua on 18 April 1957,[21] and later headed to Wellington on 9 May 1957 where she spent time at the Animal Ecology section of the Department of Scientific and Industrial Research.

[26] She later visited these islands again in December 1958, with the addition of Tucks, West, East and South Spences, Little Green, Penguin Islet, Apple Orchard and Samphire.

[42] Between 27 January and 5 February 1994, Gillham spent time travelling around Zimbabwe, as well as spending a full day in Botswana, joining a sail along the River Chobe boundary of Namibia and also participating in a walk across Victoria Falls bridge to Zambia.

[49] During her lifetime Gillham reached thousands of people during her lectures, guided walks and study tours, with whom she shared her wealth of botanical knowledge and interest in our natural heritage.

After her death she left behind a huge expanse of scientific data, including species lists and notes on conservation/land-use change, all hand written on paper.

The project also engaged people with their local biodiversity and heritage through wildlife recording and outreach events, an exhibition, and through the creation of interactive online resource.