It's somewhat frustrating that people who do not know who attended the demonstration are telling me that I'm wrong when I say it was mostly comprised of recognised far right groups.
The protests were organised by far right groups such as FLA / DLFA, with calls from people like Stephen Yaxley-Lennon and Paul Golding for people to attend.
Here's a photo of a Britain First flag: https://twitter.com/harshmallow01/status/1272099528175386625... (This is the un-modified version).
Here's Stephen Yaxley Lennon calling on the Football Lads Alliance (a recognised far right leader talking to a recognised far right group) https://www.hopenothate.org.uk/2020/06/08/football-hooligans...
Here's a right-wing source, describing a right wing PM who calls the protest "racist thuggery". https://www.telegraph.co.uk/news/2020/06/13/black-lives-matt...