This type of helmet is called a sallet. It dates from the time of the Wars of the Roses and was kept in St Mary’s Guildhall as part of the city armoury. It was made around 1460 by Martin Rondelle of Bruges, who made some of the best quality armour in Europe. Coventry's Carpenters Company accounts for 1458 list ‘Paid for Salet to ye Craft 3 shillings 3 pence’. Perhaps it could have been this sallet.