Loads of cops around generally, including the usual helicopter but also TSG, horses and dogs, though didn't see anybody let the dogs out (yeah yeah, but actually it was quite hot and it can't be good for them to sit in a van). Generally they prevented any mass meeting of groups - there were some outlying Free Tommy folk who peeled off to heckle and make a half-hearted attempt to get closer, but the cops blocked them and the only one I saw get through had his flags taken off him and was furious. It was antifa who made the most effort but there were too many cops around. They got diverted via lots of side streets but never got into direct contact.
After the "official" rally (a big black bus outside the BBC run by tr dot news, with some speakers and bad poetry) there were lots of tommyists in the pubs around the area, and the hoolie contingent were wandering and looking for a fight, but there weren't a huge number of them.
I understand that later on, after a few stellas at the All Bar One on upper Regent Street, some thought it was a good idea to go down to Westminster Bridge and block it and also hijack a tourist bus.