It meant despair for three-time Olympic Games champions, twin brothers Pavol and Peter Hochschorner of Slovakia, who took bronze.
Afterwards, Florence said: 'When we look at how to do C2 well, we look at the Hochschorners. We look at every single race they do and we watch it on video, every single turn.
'We are just pleased and honoured to have beaten them today.'
Asked about the future, Hounslow said: 'I've not thought past tomorrow morning. Should we decide to retire, we have a lifestyle guy who can help us out should we decide to go into looking for a job.'