I'm dubious its a toggle. It has no hole which is expect to be standard. It's definetly old and an Iron Age origin wouldnt surprise me though im more inclined to believe it's more medieval. But identifying what it is first has to be priority. Thanks for your helpHave you gleamed the PAS site yet for examples.
The toggles on the Colchester site shows one hole in the toggles.
Celticfasteners
www.colchestertreasurehunting.co.uk