After the death of Benjamin Disraeli in 1881, Robert Gascoyne-Cecil, 3rd Marquess of Salisbury, became leader of the Conservative Party. He was in the unusual position of leading his party from the House of Lords (and to this day the last to do so), so Sir Stafford Northcote served the role of leader within the House of Commons. He led a minority administration, so was unable to secure much legislative change, but he did call for improvements to working-class housing, in spite of being accused of championing 'state socialism'.
Editors. "The Marquess of Salisbury becomes Prime Minister for the first time". The Literary Encyclopedia. First published 30 August 2013; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1864, accessed 26 April 2015.]