Bolting onions

My curiosity has been piqued by a bolting onion near the pond.

I’m not sure I ever planted an onion set in this place, so I’m baffled as to how it ended up here. Perhaps it ended up by the pond after a bird had moved it or perhaps it got dispersed by the wind at some point. Or perhaps I’m just forgetful, as there are other onions dotted about round the garden, where I placed them because I didn’t have a dedicated space for planting them all together.

Anyway, I’ve been watching with interest over the past months. And now quite clearly there appear to be new onion sets at the top of the stem. I’d expected a flower which produced seeds and therefore wonder if it is in fact a normal onion or one which has hybridised.

The above photo shows walking onions which are now forming their own sets in order to walk across the garden. They don’t seem to have done any walking yet and the original bulb I am curious about didn’t look look like a walking onion before it bolted. However, could the walking onions be a source of hybridisation?

So, if anyone has any answers to my questions, I would be interested to know.