‘Chances are, that he din’t swallow it at all, and that you’ve missed it. A piece of glass that big would probably cause problems had he tried to swallow it. If he has somehow swallowed it, such a big piece would be easy to locate with a CT scan, and remove, if necessary.’
I’m afraid I have to disagree – the visibility of glass on x-ray imagaing (which is also what CT is) depends on the lead content of the glass itself. Lead crystal glass is seen more easily because it has a higher density so attenuates x-rays better.
‘Chances are he’s not swallowed it 2 years olds have tiny gullets a piece that size would harm him straight away and he’s be in pain.’
Again, sorry to be alarmist, but he’d easily be able to swallow it.
I suspect that nothing would however be done other than watch and wait unless he has clinical symptoms but this is not something that should be or can be advised without examining him so I would reccomend you take him to accident and emergency and have him formally assessed.