Thank You for the replies.
He has had egg only once before. He was 8 months and vomited so badly that haven't tried it since.
So I can't say for certain that, that was the problem.
Everything he ate that evening he'd had before. Homemade chips, Sausages and beans. The sausages I buy from the butchers, which he didnt eat. The only thing different were the baked beans. Normally, I buy Heinz, but this one occasion I bought some from Aldi. That being said, he has had them in the past.
He doesn't have an epi pen, it's been so long since we've had a reaction to anything I was hoping he was growing out of it.