This thread has made me laugh
Recalling a spaniel is not easy BUT it can be done.
Firstly nothing will work for recall unless he loves it more than what he is chasing after (obvious I know)
Most toy orientated dogs are easier to train than food orientated dogs as the reward lasts longer. Think about a Labrador recalling for food it take a millisecond to swallow the reward but a dog that will play tuggy or ball gets several minutes of reward.
So first you need to become really really interesting to your dog. Yep more interesting that squirrels in the wood. You need to work on this is in a boring place to start with so in your kitchen find out which toy he loves, is it a tuggy, a ball on a rope, you can get some rabbit skin covered tuggies (terriers, and spaniels usually love them).
Another thing to try is without toys or treats can you make your dogs tail wag - again with a spaniel, lab or goldie you just have to smile at them! but make it really wag make them go crazy with excitement - maybe by making a high pitched noise, or jumping up and down, or rolling on the floor see which of these is more interesting to your dog. One of mine dogs loves it when I sneeze and he always comes charging over tail wagging.
So now you know what on your own makes you interesting to the dog
and which toy they love.
They only ever get this toy on very very special occasions with a spaniel I would show them the toy and run away really really fast 99.9% of dogs will follow you (especially if you are making that high pitched noise that makes his tail wag- you may get arrested but never mind!)
All of the above should still be done in very boring places without distractions for a while and only now and again.
Gradually up the distractions see if he can he still recall to you if the children are running around, can he still concentrate on you if someone else is squeaking a toy, can he recall to you if another dog is nearby, can he recall to you if there is a squirrel running by. When he can concentrate with distractions then you are ready to go out on location!
Also get a clicker every now and again at random intervals say the dogs name - they will look at you and click - this just keeps them guessing and reinforces that their name is great.
When out on walks you want to avoid the spaniel ever getting onto a scent or seeing a squirrel and starting the chase - so again (yep hard but very doable) you need to interact with your dog all the time on the walk. I would have a long lead and a harness on and let the dog drag the lead behind him to start with.
If he loves scenting - teach him to track but teach him to track objects you want not rabbits etc. Get him in a sit show him a favourite toy get his to "find" it (rabbit covered toys are good for this) send him to find it - you can build this up to make it harder and harder eg put the toy out of sight behind trees etc.
Teach him to track down the children, do recalls between the pair of you keep him onto you all the time - he should not have time to be left to go elf employed.
Teach him to weave through your legs, teach him to spin to the left and right so he is constantly being "worked" when out and about.
Change the routine when he can do the above think of more ways to keep him with you and you to be interesting.
Sorry gone on a bit - I do realise how frustrating this is (having owned gundogs myself) do not expect things to change overnight but you can turn this around with practice and patience.