Mathematician. Mordell was born in Philadelphia, the third child of Lithuanian immigrants. He had an interest in mathematics from an early age and though having no specialised training he was well advanced in the subject by the time he entered high school. In 1906 he paid for a one way ticket to England to sit the Cambridge University scholarship exam. He finished top of the list and was awarded a scholarship at St John's College. In 1909 he was Third Wrangler in the Tripos exam and, though there was no great interest in his chosen subject of number theory, Mordell was subsequently awarded the Smith's Prize.
In 1913 Mordell took up a lectureship at Birkbeck College, London, where he remained, with an interruption for war work at the Ministry of Munitions, until 1920. Moving to the Manchester College of Technology he produced his most important work, his 'finite basis theorem'. This states that the rational points on a non-singular plane cubic can all be obtained from a finite number of them by a definite process. In 1922 Mordell took a readership at the University of Manchester and was appointed to the Fielden chair of pure mathematics a year later. In 1924 he was elected to the Royal Society and took British nationality in 1929.
In 1945 Mordell returned to Cambridge to take up the Sadleirian chair, also being elected to a Fellowship at St John's College. He retired from the Professorship in 1953 but continued working, publishing and lecturing. A keen traveler, he was delighted to accept visiting professorships from all parts of the globe. He died in 1972.
Mordell was awarded the Sylvester medal of the Royal Society in 1949. He was president of the London Mathematical Society (1943-5) and received both its De Morgan medal (1941) and its senior Berwick prize (1946).
Though more than an able mathematician, Mordell was probably better known as a research facilitator. An enlightened head of department and very concerned with the quality of teaching, he created an extremely strong school of mathematics, both at Manchester in the 1930s when almost every young mathematician of note seems to have passed through his department, and at Cambridge. He was also very influential in the assistance he gave to refugee mathematicians from Germany and Italy in the 1930s and 40s.
He married Mabel Elizabeth, the only daughter of Rosa and Joseph Cambridge, in 1916. They had a son and a daughter.
Correspondence between L. J. Mordell and fellow mathematicians, family and friends; assorted papers on mathematical subjects; lecture notes.
Given to St John's College Library by Professor Cassels, July 1972.