LO banging his head

Hi Mummies,

I have a one year old who 99% of the time is an absolute angel. No joke, he makes me look like a pro at parenting.. I'm not, I was just blessed with an awesomely behaved kid.
But, that little 1% of the time, he is a nut case. He has a temper, a really horrible one. Admittedly, that comes from me.. However, I don't let my temper show infront of him.

Anyway, if he cracks the shits about something, he throws himself backwards, whacking his head on the ground. He's only done this at home. (He's never naughty when we are out). I don't know why he does it, or how it came about.. Even if he's sitting in his high chair, he even does it in his high chair.

Yesterday he did it on the concrete patio because I told him not to eat grass..

Does anyone have any suggestions on how to stop him from doing it? I'm scared he will end up seriously hurting himself.

Thanks in advance x