top talent - may made unfortunate appointments, including a chancellor she regularly locked horns with.
personal qualities - cameron was always on top of his brief but sometimes took decisions too quickly. johnson had a clear vision to take britain out of the eu
leadership in opposition - lack of experience as leader of the opposition was a handicap for major, brown and may. blair came to tenure after labour had spent 18 years in opposition, meaning his top cabinet members had no previous senior cabinet experience. cameron came after 13 years in opposition.
elections and majorities - blair 179 1997, johnson 80 2019
media - major ridiculed by spitting image as dull. blair and johnson used the media effectively
economy - major 1992 suffered troubled economy which prevented him from enacting policy. brown able to turn the 2008 crisis to his benefit by his skilful handling of international leaders, such as the G20 summit in london 2009.
luck and timing - thatcher in power as cold war was ending and could play a key mediating role between reagan and gorbichev. thatcher had weak opposition leader (michael foot), and so did blair (hague and ian duncan smith). blair was strong opposition to major. brown faced difficulty purely due to the time he rose to power