It’s strange to think of a parish church without an organ. It’s so automatic to sing hymns in churches, we barely think about it - yet it was not always so.

Organs were commonplace in churches from the 10th century, but at first they were used only for instrumental music. That all changed with the Tudors, under whom theatre and music flourished. The music sung daily by cathedral choirs today still includes pieces by royal composers from that era, such as William Byrd and Thomas Tallis.

This golden age for composition was to be short-lived, however. The English Civil War brought to power the Puritans, who disapproved strongly of music both inside and outside church and ordered the destruction of all organs in the 1640s. Almost all were broken up and sold for scrap.

Although this law was reversed only 20 years later with the restoration of the monarchy under Charles II, it was too late. New organs were very expensive, so most parish churches had to make do without one for the next 150 years.

By the mid-1700s, up-and-coming towns like Truro were desperate to get their hands on an organ. New hymns like John Newton’s Amazing Grace and Charles Wesley’s Love Divine, All Loves Excelling became hugely popular.

From the mid-century onwards, no fashionable church was complete without six elements: steeple, box pews, pulpit, gallery, clear glass windows - and an organ. By 1768, Truro’s St Mary’s Church had them all.

Local businessman William Lemon provided the money needed to pay for a new organ. Made by John Byfield and originally destined for the Chapel Royal in St James's Palace, it was brought all the way from London in 1750.

There was a slight hitch when the trumpet-blowing cherubs on the top were too tall to get into the church. They had to be taken off and now stand on top of the screen behind the high altar.

The Byfield Organ later had a starring role as the instrument on which the first ever Nine Lessons and Carols service was played, on Christmas Eve 1880.

Believed to be the oldest pipe organ in Cornwall, the Byfield Organ stands in what is now St Mary’s Aisle – the last remaining part of the historic parish church that remains within the cathedral. The aisle has just re-opened following major roof repairs, and you are invited to listen to the organ being played at a special celebration, with free children’s activities, this Saturday from noon to 3pm.

On Saturday evening, Truro Cathedral Choir will include William Byrd’s Sing Joyfully in their Summer Concert from 7pm. For full details and tickets, visit www.trurocathedral.org.uk