It may be possible the dog felt threatened or cornered, especially in view of the fact he has lived with youngsters before. He may well have been punished or frightened when a puppy and therefore anxious around children or food. Some people do the strange thing of taking food away from a dog and punishing him when he objects.
I would teach a Swap rather than a Leave. It is easier and kinder - and leaves both parties feeling they`ve gained.

Can I ask, how did your daughter try to get the lid from him? I would have expected the bite to be to the hand/arm rather than the foot and calf.

Resource guarding is easy, as long as everyone follows the rules I have a dog that I adopted at 7 years old that was severe... he was biting, lunging, scattering his food. it took only 6 weeks to solve his food guarding. a little longer to solve his people place guarding.

I also had a dog with food guarding issues. He never stole, he'd wait to be given the 'ok' to eat, but once the raw meaty bone was his he was prepared to defend it.

I solved the problem 'a la Cesar'. Never feed an excited dog! I put that into practice - sometimes staying up to 2 o'clock in the night before feeding him. But it worked. Eventually he realised that any sign of excitement -pacing, barking, whining, drumming of feet meant no food.

Took a while but I won. To the point that if I just stood still next to him (perhaps waiting for the kettle to boil) he would drop the food and walk back a pace or two waiting to see what he should do next.

A unique approach I have never heard of before.

the culture clash by jean donaldson is also a really good read and will give u a clue into his behaviour.

I hope it works out for you all, well done for taking the first step and coming on here asking for help instead of just giving up on him.

I am a dog trainer that lives in Hertfordshire as well, I also perform home visits and behaviour consultations with many years expereeince of rescue dogs and aggression problems, if that is of any use to you.

Weird. I prefer to train a dog. Life`s too short to fight your pets simply to make a point.

I'm not a fan of Cesar. I believe his methods can work, but not for the right reasons, so I'll leave that without comment.

I'm glad your daughter will get on board. It sounds like you are a great family for him, and he will get over this. Let us known if there is anything in the book that you'd like clarification on or anything we can do to help - I've got my fingers crossed you see results and are feeling inspired and in control very soon

Excitement can lead to aggression. By removing the excitement, the aggression didn’t happen.

By the way – this behaviour modification had a serious side effect! The dog’s recall became 100% from about 30%. So anybody having problems with recall – might be worth looking at all aspects of your dog’s behaviour and seeing if changing ‘goofy’, skittish’ or ‘dizzy’ behaviours into more calm and focused behaviours make a difference in other areas of your relationship - particularly the recall.