The illegal break-up of a £3 million Viking hoard of "national importance" that marks the beginnings of a unified kingdom of England represents a theft of the country's past, an expert has said.

The 300-coin hoard and its priceless jewellery dated to around the ninth century.

It was a tumultuous period of history in which Alfred the Great, then just King of Wessex, fought a series of battles against the Vikings.

Probably buried by the retreating Vikings, the trove was dug up 1,100 years later by metal detectorists George Powell, 38, and Layton Davies, 51, on Herefordshire farmland, in 2015.

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The pair have now been convicted at Worcester Crown Court of stealing the find, illegally concealing it from the authorities and then selling off coins to private collectors.

A jury also found two other men, 60-year-old Paul Wells and Simon Wicks, 57, guilty of conspiring to conceal the hoard.

Wicks was also found guilty of helping sell off the coins for cash.

Dr Gareth Williams, curator of early medieval coinage at the British Museum, said: "It is not just the theft of the objects that is important in this case.

"It is the fact that the knowledge has effectively been stolen from everyone."

He added: "It dates from after, I would say, Alfred has got that new ambition of being king of the Angles and the Saxons.

"You could say it's the first hoard of this newly united kingdom that would later become Anglo-Saxon."

The trial heard only a single silver ingot, three jewellery items and 31 of the coins have been recovered.

Photos on Davies' phone – deleted and then recovered by police – showed many more items dug out of the ground on farmland near Leominster, including more ingots and up to 300 coins.

Among the coinage were five rare "Two Emperor" pennies suggesting an alliance between Alfred and the last King of Mercia, Ceonwulf II, and bearing both men's image, worth up to £50,000 apiece.

There was also a "hugely significant" gold serpent's head arm bangle and "showpiece" gold ring, both from the era, and a fifth-century rock crystal pendant intricately chased in gold, probably of Frankish origin.

The items recovered – including five coins found stitched in the lining of a magnifying glass case – are now safely under lock and key at the British Museum.

Explaining the hoard's importance, Dr Williams, who gave expert evidence during the trial, said: "It is potentially extremely important.

"The difficulty is we don't have all of it and therefore we can only guess at the full importance."

He added the find was discovered before the Watlington Hoard, from the same era, in 2015, and was probably buried earlier.

The trove was likely looted by Vikings, with Dr Williams adding it was originally "likely to have been sitting in a royal or church treasury somewhere", and Leominster was the site of an important monastery at the time.

"If we had the whole of the two (hoards) we'd have a much clearer understanding of that period," added Dr Williams.

Turning to the loss of much of the Leominster hoard, he said: "This is a find of national importance from a key moment in the unification of England.

"So it comes just at the moment when the Vikings were attacking in a large way.

"There were several different Anglo-Saxon kingdoms, two of which had already been defeated and conquered and a third was struggling.

"What this (hoard) shows is the king of Mercia, Ceolwulf II, was involved in an active alliance with Alfred of Wessex."

Little is known of Ceolwulf other than he reigned for five years, 874-879.

The coins marking the alliance were then driven out of circulation by Alfred soon afterwards, with only "passing references" which are dismissive of Ceolwulf in accounts of the time.

Dr Williams said: "In 879, Alfred is starting that process of re-writing of history."

He added: "Ceolwulf is completely dismissed, and yet the coins with these two hoards, is showing the alliance between Alfred and Ceolwulf.

"Then he just mysteriously disappears .

"All of a sudden Alfred has got his kingdom and in fact is then dividing up that kingdom.

"You'd think him getting hold of another kingdom would be worth celebrating, which suggests his getting hold of it was not entirely creditable.

"The hoard sheds some light on that period."

Dr Williams added: "All of that is lost.

"We will probably never know entirely what was in it.

"I am still hoping more may yet be recovered.

"One of the things we will be doing, once this case is over, is looking at things in more detail, because everything has been sitting in evidence bags in a cupboard."

Powell, of Kirby Lane, Newport; Davies, of Cardiff Road, Pontypridd; Wells, of Newport Road, Cardiff, and Wicks, of Hawks Road, Hailsham, East Sussex, will be sentenced at a later date.