Much on my cycling on tadpole is rural though that does involve passing through some towns and some busier B roads.Are you a rural rider Psmanthe? The hedge rows may be 'denuded' so that they see you earlier, with leaves ,hedges will obscure the view.
I have cycled through larger cities (on tadpole) but in France, Belgium, Netherlands. where drivers and conditions are very different.
I do normally use a flag though not certain how much it helps but my theory (unproven) is that it will show above some hedgerows for drivers to see. I've no idea if it has any impact but I can't think of negative impacts, just potential positives.
Ian