£4.3m hoard acquired for the nation by South West Heritage Trust will be displayed at British Museum next month

It began with a speculative trip to a soggy field in south-west England by a seven-strong band of metal detectorists more intent on figuring out how to use some new kit rather than unearthing anything of great historical importance.

But the friends came upon an astonishing hoard of coins – 2,584 silver pennies – from the time of the Norman conquest, which has been valued at £4.3m, making it the highest-value treasure find ever in England.