[1][2] He was a member of a circle of researchers that included George Dantzig, Abraham Charnes, W.W. Cooper, William Orchard-Hays, Martin Beale and others.
He is the author or coauthor of at least a dozen books on mathematical programming, game theory, manpower planning and statistics and of many journal publications and conference papers.
The plan was to reunite the family in England and then leave for New Zealand, but before that could happen, the Second World War started and the Vajdas were briefly interned as "enemy aliens".
Steven stayed with the Admiralty until 1964, holding such appointments as Assistant Director of Operational Research and Head of the Mathematical Group.
Upon his second "retirement" in 1967 he continued at Birmingham in a research appointment in mathematical statistics, working with Henry Daniels, David Wishart and Vic Barnett.
He remained an active member of the Sussex staff until he died in 1995 in Brighton, two years after the birth of his first great grandchild Alexandra Eva (named after his wife).