Medal card : Pte. - 25th London Regt. Card address - 21 Belmont Rd, Twickenham.
Medal roll : 25th London R. Pte., Attached Infantry Base Depot 1(a) France 7.8.18 to 18.8.18.,
                   Posted to 10th London R. 1(a) France 19.8.18 to 25.9.18.

Ronald Hare was born in 1899. He served in the 2/25th London Bn. He served in France in 1918, as far as I can ascertain it most most likely that he was attached the the 10th London Bn. He wrote a diary of his time in the war, albeit a short time, in which he was wounded.

His war diary - Note this is a PDF file.

Ronald Hare trained a as Doctor and became involved in medical research. It was Hare as Professor Fleming's assistant who made an extraordinary discovery. Although Alexander Fleming discovered penicillin in 1928, he didn't know why it worked. It was Hare who was able to point out that the penicillin had worked only because of an unusual change of temperature at that time of year. Referring to the London Meteorological Records for that fortnight in July 1929, Ronald Hare discovered that there had been a nine day period of unusual cooler temperatures. This favoured the growth of the Penicillium mould. Penicillium grows at 25 C. The Staphylococcus at 35C. All over Europe, laboratories had tried to replicate Fleming's discovery but could not make penicillin work. Ronald Hare's work showed how.

In 1936 Professor Hare was appointed Research Associate at the University of Toronto and later was largely responsible for the planning and building of the Penicillin Production unit set up by the Canadian Government.

His full working history from the Wellcome Library :-
Hare was a bacteriologist of repute working through an exciting period in the history of the discipline. Among other activities he reported on the scientific value of bacteriological experiments undertaken in German concentration camps during World War Two [see PP/HAR/B.7]. He was also an historian of the subject.. 
Educated at the Royal Masonic School, Bushey, Herts, 1910-1917; Birkbeck College, 1918-1919; 
Worked at St Mary's Hospital: LMSSA, MBBS, 1919-1924; Research scholarship, Institute of Pathology and Research, St Mary's, 1925; Assistant, Inoculation dept, St Mary's, 1926-1930; 1st Assistant, Research Laboratories, Queen Charlotte's Hospital, London, 1931-1936; Canada: Research Associate, Connaught Laboratories, University of Toronto, Lecturer in Department of Hygiene and Preventive Medicine; largely responsible for planning and building of Canadian Government penicillin plant at University of Toronto, 1936-1946; Professor of Bacteriology, University of London, 1946-1964; Honorary Consulting Bacteriologist, St Thomas's Hospital, 1951; Member of Council of Wright-Fleming Institute, 1952-1960; Emeritus Professor of Bacteriology, University of London, 1964;
[This paragraph and diary with acknowledgments to the Wellcome Library]

Professor Ronald Hare became Emeritus Professor of Bacteriology in the University of London. He died at the age of 86 on the 13 Mar 1986.

[Acknowledgments also to Wikipedia]