Dick Newby, his successor as the party's chief whip in the upper chamber, said: "John was, throughout his life, a great servant to social democracy and liberal politics in Britain.
"He was a passionate believer in the European project. He always fought for the idea that Britain's best interest was working together with our friends across Europe to build a better future for us all.
"He was a great mentor of mine, a fine European and a widely respected chief whip. He will be deeply missed."
"John served as chief whip in both the Commons and the Lords and proved to be a natural in the role. He was a great mentor of mine, a fine European and a widely respected chief whip.
"He will be deeply missed."
Lord Roper was Labour's spokesman on defence from 1979-81 and SDP chief whip from 1981 to 1983.
From 2008 to 2012 he was principal deputy chairman of Committees of the House of Lords and chairman of the European Union Committee.
Source: http://telegraph.feedsportal.com/c/32726/f/579309/s/4d3a6e14/sc/13/l/0L0Stelegraph0O0Cnews0Cpolitics0C12130A950A0CLiberal0EDemocrat0Epeer0ELord0ERoper0Edies0Eafter0Elong0Ebattle0Ewith0Eillness0Bhtml/story01.htm