[3] He served on the editorial board of The Journal of Modern History and held office with the North American Conference on British Studies.
Leventhal observed that as Koss matured there was "an increasingly irreverent and ironic tone in [his] scholarship, a willingness to criticize as well as to condone".
[1] His death was mourned in several academic books published soon after, together with that of Alan J. Lee, who had also written on the history of newspapers in Britain and who had also died at a relatively young age.
[6][7] Koss is best remembered for a two-volume work The Rise and Fall of the Political Press in Britain (1981, 1984), respectively covering the nineteenth and twentieth centuries.
A tribute volume appeared in 1987: The Political Culture of Modern Britain: Studies in Memory of Stephen Koss, edited by J. M. W. Bean, with a foreword by John Gross (London: Hamilton).