[2][3] Her obituary in the Bulletin of the London Mathematical Society noted that fuzzy topology was "the field in which she was one of the pioneers and recognized as one of the leading figures for the past thirty years.
[5] Warner had acquired various academic prizes at both the college and university level during her undergraduate degree, allowing her to progress to doctoral work in Oxford via a Research Scholarship.
The transient nature of his occupation disrupted her ability to participate formally in academia and terminated her doctoral studies at Oxford, but she continued to dedicate herself to mathematical research to the extent that the demands of being a diplomat's wife would allow.
Whilst stationed in Beijing between 1956 and 1958 Warner continued her involvement with Oxford's Whitehead research group, working alongside prominent Chinese topologist Chang Su-chen until escalating political tensions forced them to terminate communication in 1958.
Accounting to her time abroad, Warner was now on the margins of her Oxford-era interest of homotopy theory research, much of her knowledge obsolete due to significant advancements in her absence.
[4] Warner's output between 1980 and 1985 of 20 papers on the subjects of tolerance spaces and automata, and her conceptualisation of the 'lattice-valued relation' towards the end of this period rendered her eminent in the field of fuzzy topology, and these achievements culminated in her promotion to a readership at the City University in 1983, and then a professorship in 1996.
[4] The broader application of Mary's work in fuzzy topology involves the prediction of real-world events which are always imprecise – nuclear reactor failure and the occurrence of earthquakes.
[4] The improvement of education was also of significance to Warner, who served on the Court of the University of Wales Institute of Science and Technology, as the vice-chairman of the Governing Body of Geneva's International School, and as the governor of Lindisfarne College.
[4] Ill health had compelled Warner to retire a year early from her position at the City University, but she did not abandon either her postgraduate teaching or her research,[6] which was still ongoing when she died in Spain in 1998, aged 65.