Elmer was born in Llandybie in Carmarthenshire, West Wales, on 9 November 1941. He was a Welsh speaking Welshman and this was very important to his sense of identity. When he went, as a schoolboy, to interview for undergraduate places in England, he found that some of the words in the questions he was asked were new to him and he had to infer their meaning from the context in which they were used.
Elmer undertook his undergraduate studies at the University of Cambridge and his postgraduate studies at the University of Warwick. He then held academic positions at a number of institutions including the University of Hull, the Institute of Advanced Studies in Princeton, and Swansea University, before accepting a Tutorial Fellowship at St Catherine's College, University of Oxford, in 1971.
Elmer left Oxford in 1979 for a Chair at the University of Edinburgh, where he stayed until 2005. In Edinburgh he played a leading role in establishing the International Centre for Mathematical Research, a venue for international conferences and workshops that continues to play a major role in UK mathematical life. During this time he also served as Vice-President of the London Mathematical Society.
Elmer moved to Bristol in 2005 to establish the Heilbronn Institute for Mathematical Research (HIMR) and was the HIMR Director from 2005 to 2009. HIMR is now a major national mathematical research institute and Elmer’s contributions to its development have been of central importance to its subsequent success. Having the Institute's main hub here in Bristol has played a significant role in lifting the University of Bristol School of Mathematics into the highest international divisions.
When Elmer retired in 2009, HIMR held a conference to mark the event. Elmer was pleased that the coffee mugs provided for the participants carried an inscription in Welsh: "er nodi ar derfyn teyrnasiad Elmer". We were told that this meant "to mark the end of Elmer's reign", although, characteristically, Elmer said he could have provided a more poetic translation had we asked him.
2009 was marked not only by Elmer’s retirement but also by his being awarded a CBE in the Queen’s Birthday Honours for his contributions to UK mathematics.
Following his retirement, Elmer was appointed as an Honorary Visiting Professor by the University of Bristol - an appointment he would hold right up until his death.
Elmer's personal research interests were in geometry and topology and his publications cover the full range of this broad field. He had a longstanding collaboration with Victor Buchstaber of the Russian Academy of Sciences and they did important work together that continues to be highly influential.
Elmer had a marvellous sense of humour and a seemingly endless collection of excellent anecdotes. He knew all of the important mathematical news before anyone else. Combined with an underlying seriousness of purpose and an excellent mind for strategy, this made him a wonderful academic leader. It also made him an outstanding mentor; he took a genuine interest in people, thought carefully about what they told him, and gave deeply insightful advice. Many mathematicians have commented on the help he gave them early in their careers.
Elmer had an exceptional capacity for friendship. He went into hospital soon after his retirement and there, in the same ward, met the double Oscar-winning cartoonist Richard (Dick) Williams, who went on to became one of his closest friends. Dick drew a beautiful portrait of Elmer that appeared on the poster (and coffee mug!) for the HIMR Conference celebrating his 70th Birthday in 2012.
Elmer was a first-rate mathematician and a brilliant academic leader whose visionary contributions have had a major impact on mathematics. He will be greatly missed by his many friends, his family, by those whose careers he progressed through his mentorship, and by mathematicians worldwide.
To honour Elmer's life and his contributions to UK mathematics, HIMR will be holding a one-day Elmer Rees memorial conference on 10 February 2020. Please see the HIMR website for more information and to book your place.