This is from 'What UK Thinks', its their 'Poll of Polls'

  • The average of the six most recent polls
  • Fieldwork conducted between 14 and 20 June 2016
  • Based on two (online) polls by YouGov, two (phone) polls by Survation, one (online) poll by Opinium, and one (phone) poll by ORB
  • The most recent additions are one poll by YouGov (17-19 June), one by ORB (14-19 June) and one by Survation (20 June)

From the same people, a view over time: