For anyone who calls out "on your left/right" or variations of it might be worth bearing in mind a couple of things.
Not everyone on a bike is a cyclist and knows "the lingo". A sudden shout of "blah blah RIGHT!" can easily mean the person in front pulls right.
The worst example I've ever witnessed of this was a peleton terrorising twin girls, no more than 8 years old.
Doubly significant on cycle paths / mixed use paths where there's more leeway to veer left or right.
Not everyone speaks English!
Rare, yes, but possible. That bike, loaded down with panniers may not be a local!
Personally, I'm a big fan of bells, although I understand that they're not that popular in the UK. That's a pity. If cycling is ever going to hit a critical mass, the communication between cyclists (and pedestrians) will have to improve. Any town or city in NL in the morning rush hour is a symphony of bells!
As for the OP, it doesn't matter what people on here say they'll do. It matters what your experience is. A mirror is a great way of keeping an eye on what's happening behind you.