Take your big, city whistle!
Won't stop the loony pedestrians, the space cadet dog walkers etc from wandering across the path. They feel that cycles are not included in the shared environment concept.
But you might feel better about having alerted them to your presence. All that, just before you hit them.
Or worse get brought down by their extended dog leads.
All that and the "I haven't ridden a bike for 20 years!" brigade.
The cadre who cannot work out which side of the track they should use, so wander from side to side and behave as if they are in a slow cycling competition.
Then there's the clay pigeon model. A group wandering lost in conversation in a world of their own. You alert them to your presence.
Failing the loud whistle it seems some sort of group telepathy works.
One member of the group will casually look over their shoulder in your direction. Turn back to face the front and continue wittering. Something may prompt another member to look behind. They may or may not see you. That's the invisibility cape you picked up in Poundland at work.
Then the group realise you are behind them and closing in.
At your shout, bell, whistle they respond like pigeons in a shoot.
Those on the left will move straggling to the right and of course those on the right will bump into the left party as they move to their left.
The result is that whilst they all responded to the threat you pose they have successfully managed to continue to block the whole path.
Finally there is the victor ludorum of the pedestrian party, the headphones wearer. Lost in whatever world these Tardis headphones transport them to, they are oblivious of your presence.
These devices have so reduced their brain capacity that they are scarcely aware of what's in front of them. They have completely disregarded that their new world includes a "he's behind you sector"
