Toilet seat identification/help

Hoping someone can help with this toilet seat which has broken lid.

I've looked at the brackets and can't see how the seat comes off. Doesn't seem to be any screws or fixings to undo.

Can anyone advise how the seat is removed and a replacement one so I can refit it, it's an odd shape.

Thanks

It could be the type that slide onto a plate mounted to the pan so you could try carefully and evenly trying to slide both hinges at once towards you to see if it moves on a baseplate or the fixings most likely go through the bottom of the hinge mechanism and have a nut on the underside so have a feel below the pan for any fixings. A small mirror may help you see if you don't fancy putting your hand down there if you are scared of spiders etc...

Thanks. I can see a small hole on the back of the bracket. I guess an Allen key fits in it?