An astonishingly well-preserved medieval brooch featuring what could be dragon and dog decorations is among a record number of objects discovered last year by the nation’s army of metal detectorists.

The British Museum on Tuesday announced that 1,311 finds which are defined as treasure had been found by members of the public across England, Wales and Northern Ireland in 2019.

They also included an iron age drinking set, a solid gold bronze age arm ring and a coin which helps tell the story of Carausius, a usurper emperor who in 286AD broke Britain away from Europe, in an adventure which ended badly.

Michael Lewis, the head of the British Museum’s portable antiquities scheme, said the 1,100-year-old brooch discovered in Norfolk was a particularly striking and rare discovery.

“It is an amazing example of Anglo-Saxon art of the period,” he said. “When the finder found it the reaction was, is this old? It could be something more modern which was inspired by the past. Your gut reaction might be that it was Victorian.”

The brooch has a distinctive stylised Anglo-Saxon decoration called Trewhiddle. It features plant motifs, geometric design and animal art which seems to include boar, dragons and dog-like creatures.

“On the back it still has its catch plate so in some ways you could almost pop it back on and wear it again, it is in such good condition,” said Lewis.

It was found in Great Dunham but the topsoil was composed of recently delivered soil from a tipper truck. That means it could originate from the Pentney area, which would make sense given its similarity to spectacular brooches from there that are in the national collection.

In total, 81,602 finds were recorded with the portable antiquities scheme. Many of them may not appear to amount to much but they were all important, said Lewis.

Facebook Twitter Pinterest Early Medieval silver and niello brooch Photograph: British Museum

“The reason we record these objects is the history, what they tell us about the past. The fact that a lot are fragmentary, broken, damaged etcetera doesn’t really matter. Together they paint a picture of what was going on in particular parts of the country at particular times.”

Take the Roman Britain coin, known as a radiate, found in Headbourne Worthy, Hampshire. “On the face of it, it looks a grotty old coin, which it is, I guess,” said Lewis.

But it helps tell the story of Carausius who declared himself emperor of Britain and northern Gaul between AD286-93, breaking away from the Roman empire. He was assassinated by his treasurer Allectus.

The newly found coin is just one from an astonishing variety of nearly 4,000 which were struck during Carausius’ reign.

Other finds include a pure gold arm ring weighing 300g and dating from the eighth century AD which was found at St Bees, Cumbria.

It has shallow punched dots as decoration and is similar to rings found in County Donegal in Ireland and Buckinghamshire. It has noticeable wear, suggesting it was frequently worn by the wealthy person who owned it.

In Lenham, Kent, a detectorist discovered a hoard of iron age drinking vessels which include a particularly rare bucket decorated with hippocamps – creatures with the head of a horse and a fish-like tail.

Treasure objects are generally defined as gold and silver objects that are over 300 years old, or groups of coins and prehistoric metalwork. Around a third of the objects found last year have been acquired for museum collections.

The culture minister, Caroline Dinenage, said it was brilliant so many were going on display in local museums. “Each one of these valuable discoveries tells us more about the way our ancestors lived and I want to congratulate all those who played a part in helping uncover more about our shared history.”