Hello Rachel,although I am not in your area we had a recent story in the local paper "TWO tonnes of coiled spikes, thought to be anti-tank devices, have been removed from a section of Northam Burrows’s Pebble Ridge. The recent high tides had exposed the coils and were thought to be erected at that location more than 60 years ago because of the natural gap in the sand dunes."
I wondered if this was similar to your recent find,but only a suggestion
Pat Adams - Flickr - BLOG
Hi Rachel
Having had a close look on the beach, I couldn't see any evidence of bits of metal. I did, however, find what I think might be the source of your question. There are a number of disks, upto 10 cm diameter, that look at first glance like rusted metal. These are actually bits of fossilised clay or shale that are regularly exposed by coastal erosion. The only metal I could find was remains of the dragon's teeth and rusted scaffold poles.
I hope this answers your question. If not, perhaps you could take a photo of the mystery items for us.
Ian