Probably Crocosmia. If you're lucky they might be one of the larger flowered Crocosmias. Or maybe just the common 'Montbretia' which is hard to eradicate. My only doubt is that mine (which I have spent years trying to get rid of) still have leaves on them. Did you see any?

Yes they are similar, but my crocosmia monbretia are smaller and have a coarse skin (like a crocus bulb). These are bigger and have smooth, pink skin. There was no foliage visible, but some of the bulbs are sprouting. I hope it's an exotic cocosmia ... the person who had the allotment before me was a gardening journalist and got all kinds of freebies.

I, also, would vote Crocosmia.

That sounds promising - better than the common old Montbretia. The link show 'Lucifer' corms. What do you think?

Here is a link that might be useful: Lucifer

Well done guys, that photo link is a positive ID. They are surely crocosmia, the only remain question is what variety. They're safe in a pot of compost, so I guess I'll find out next year. I'll post of picture of the blooms.