The left wing/Momentum are incredibly well organised. You only have to look at the numbers following JC around the country and the fact that wherever May goes is always publicised and hence there is always a counter demonstration of Corbynistas (JC keeps his speaking engagements secret, restricted to those who are knownto be supporters hence no counter-demo, not that it is in the Tory psyche to demonstrate). It is comfortably within their skill set to manipulate the BBC processes and con them into thinking they have dug up a "representative" audience whereas in reality the audience is choc full of Corbynistas. Its they way they work.
I had always thought that Momentum were a bunch of recent graduates from a former poletechnic, where they got a Desmond or Douglas in something like 'Oasis Studies'. I thought that their tactic was to openly bully and intimidate anyone who did not support Corbyn and Momentum, or any labour candidate who may have expressed doubts about the redemptive power of whole sale nationalisation and nuclear disarmament. I am now suitably chastened. I had no idea how brilliantly organised and effective they are. I am now definitely going to vote labour because Momentem are clearly the only group with the wherewithall to run the country.