Mary was passionate about the environment and spent her entire life studying it in order to conserve and protect it. She did this by working tirelessly, sharing her knowledge and enthusiasm for wildlife as well as advocating for landscapes to be protected and advising on how they could be rehabilitated. Listen to her passionate plea for conservation of wildlife written in the introduction of her Natural History of Gower book (read by project volunteer Hazel Hughes):

Industrial landscapes and protected areas

A large part of her life in Wales was spent visiting locations under threat of development and generating species list of the flora and fauna found there, this was then followed up with letters recommending the site be preserved. Some of these were successful, like stopping industrial expansion at Llantrisant Common and Nelson's Bog, whereas Mary was not so successful in stopping the "ill conceived and totally irrelevant Taff barrage" in Cardiff Bay. During this time there was big push by the Wildlife Trusts to purchase land to make them into nature reserves and Mary's detailed species lists contributed to a number of sites being selected for protection including Coed y Bedw (which Mary herself contributed to the purchase of), Lavernock Point, Llyn Fach, Coed y Bwl and the Taf Fechan Reserve at Merthyr Tydfil. Some sites such as the Pwll Waun Cynon reserve in Mountain Ash were donated to the Wildlife Trust by Lord Aberdare.

Another aspect of her work was assisting the transformation of industrial sites to wildlife havens and public amenities. By the 1970s the extractive industries (mining and quarrying) were starting to decline and with the Aberfan disaster fresh in recent memory there was a focus on making industrial sites safe as well as encouraging wildlife to return. Mary advised on suitable planting schemes for the ex-quarry and landfill site now known as Cosmeston Lakes Country Park and contributed to the development of other sites such as Clydach Vale Country Park, Dare Valley Country Park and Glyncornel Local Nature Reserve

Mary also recognised the importance of Wales' industrial heritage. Once the mines and quarries began to close, the railway lines like the canals before them fell into disrepair and became covered by housing developments, industrial units and superstores. Mary kept records of how places like Radyr shunting yard became a housing development, saw how the Glamorganshire Canal at Pontypridd declined and studied the ferns at the Melincwrt Waterfalls. In 1967 Mary, with Mairead Sutherland and the Cardif Naturalists' Society, were successful in preserving the Glamorganshire Canal at Whitchurch which later became Forest Farm Nature Reserve.

Since her days on Skokholm during Mary remained passionate about islands. Mary continued to visit Skokholm periodically but it was difficult to reach making trips infrequent. Almost on her doorstep, just 7 miles into the Bristol Channel from Cardiff, however was Flat Holm.


The plants found in an area are often intrinsically linked to the soil chemistry, underlying geology or physical features such as rivers or mountains and Mary would take these components into account when studying a location. Within Mary's archive is lots of information about geology and how it shapes a community of species. One of the Mary Gillham Archive Project volunteers, a geology undergraduate at Cardiff University, went through her archive and pulled out some of the most interesting information. 

Read about the geological component of Mary's archive here


Mary, the keen photographer, left in her archive a great pictorial record of how the landscapes of South Wales (and further afield) changed during the course of her life. Included in her photos are pictures of how landscapes changed through natural processes (eg. floods, succession), the influence of industry and infrastructure development, and how ex-industrial landscapes were rehabilitated. Mary also traveled widely at a time when International travel was uncommon, returning to the UK with hundreds of slides depicting scenes quite alien to the majority of people in the UK.

Take a look at the gallery below to see some of the changes that took place during Mary's life.  

Here's a picture of Mary standing in front of the Sgwd Gwladus waterfall near to Pontneddfechan in 1974 and the same shot - unsurprisingly similar - taken in 2017. See more Then and Now pictures taken in Shetland, Morocco, Cardiff Bay, Forest Farm and elsewhere!