Listed here are two speakers from the current protests, Trades Union Conference general secretary Frances O'Grady and Green Party MP Caroline Lucas:
The rally organizers' Facebook page (linked from the Guardian article in the second link above) lists additional featured groups and individuals:
Together Against Trump
Global Justice Now
National Union of Students
Campaign for Nuclear Disarmament
Stop the War Coalition
Palestine Solidarity Campaign UK
Momentum
Unite the Union (aka Unite)
UNISON
Stand Up To Trump
Campaign against Climate Change
TSSA - Transport Salaried Staffs' Association
Stand Up To Racism
The People's Assembly Against Austerity
Stop Trump
Owen Jones
Another Europe Is Possible
Labour Against Racism and Fascism
Together Against Trump is the group sponsoring the Facebook page where those groups are listed.
Funny how they have to have a faction for each pompous self appointed savior of the world...even though the agendas of each group are for all practical purposes the same.
Ping.