Dog barking aggressively (probably fear) whilst on walks

[Karcheer]

Ive got two Spaniels, one is 4 (Male) the other 5 (Female).

Increasingly whilst out they bark at strangers. This was initially children and only when on the lead. And now seems more frequent and on and off the lead and not just children. It isn't everyone and as far as I I can see its fairly random.

The older dog is a rescue for us although we've had her since she was 2 the other we've had since he was 8 weeks old. The rescue used to be quite nervous, but now it seems the male is more nervous and the first to do this barking thing, although it isn't always him, they seem to encourage each other.
They've been walked mostly by my husband over the summer and id not really noticed it, but I've been with them the last few days and this horrible behaviour has definitely increased.

What can I do to stop this?

Watching

Mine used to be very bad for this.

Firstly, join the reactive dogs uk Facebook page and look up behavioural adjustment.

The basic principle is to allow the dog to see the scary thing but not be close enough to be scared. When the dog looks at trigger and looks back at you for reassurance then treat with something high value. Eventually the dog will learn to look back at you for a treat and distracting rather than reacting by barking. The theory is that it also changes how your dog views things as what was once scary becomes not so scary as it involves something the dog likes.

Some people ask strangers to give the scared dog treats to try and speed up the process however I think it's best the reward comes from you rather than strangers as it teaches the dog to look to the handler rather than focusing on other people. Also I don't want mine running up mugging people for chicken

I trained all of my dogs to now watch me and sit nicely while people pass and it's so much easier!

I would be careful about allowing them off lead if they are barking at people though, really risky if someone was to complain. I always recall when around people we don't know for the dogs safety more than anything

I guess I just have to change how I walk them, they have been off lead for years and its not been a problem ie they never barked. They never react if the other walker (when off lead) has a dog.
Its all very odd tbh.
What was a fairly small issue ie barking when on the lead to small children, which I could easily manage by crossing the road. Seems to be escalating, and Ive no idea why.
Thanks for your help. Will do lots more recall (which they are both great at) when we see other people, and lots of treats when we are out and about (my male spaniel (who is a pig) is going to love this).

Definitely the "watch me" technique, as grey said. There are videos online and dogs trust have information on it too.