During the English Civil War, the cathedral was overrun by Parliamentarian troops.
Along with other destruction, the troops seized the books of the cathedral library, taking them to Cardiff Castle, where they were burned along with many copies of the Book of Common Prayer.
Among those invited to the castle to warm themselves by the fire on that cold winter day, were the wives of some sequestered clergymen.
Also during this time of unrest, a man named Milles, who claimed to be a practising Puritan, appropriated portions of the cathedral for his own gain.
Milles set up a tavern in the cathedral, used part of it as a stable, turned the choir area into a pen for his calves and used the font as a trough for his pigs.

The southwest tower suffered major damage in the Great Storm of 1703 and by 1720, was in a state of collapse.
The damage to the cathedral was so extensive that the church seriously considered removal of the see to Cardiff in 1717.
Between 1720 and 1723 a series of storms proceeded to damage the cathedral further, bringing down sections of the roof as well as other destruction.
The collapse of 1723 forced worship services to be confined to the Lady Chapel and closed the western entrance of the cathedral entirely.

Thirty years after the cathedral roof collapsed, the chapter asked an architect, John Wood, the Elder, to prepare estimates and plans to restore the cathedral.
In 1734 work began on a new cathedral, designed by Wood.
Wood produced an Italian temple style edifice, working only on the eastern portion of the building, while leaving the remaining western half in ruins.
What Wood was trying to build at Llandaff was not Italian, but a recreation of Solomon's Temple.
 Another sixteen years passed before the chapter solicited funds to repair the western half of the building.
Wood's plans were to replace the western entrance of the cathedral with a tower and rustic porch.
No changes were made to the western entrance until Wyatt and Prichard began their work in 1841, when the damage to the western portion of the structure was repaired and all traces of the Italian temple work by Wood had been removed from the cathedral.

During the 19th century the bishop began to reside in Llandaff for the first time in centuries; no bishops of the see resided in Llandaff for almost 300 years.
In 1836 there was another unsuccessful attempt to transfer the see—this time to Bristol.
After the attempt at transferring the see, the office of Dean was restored to Llandaff; the position had not been filled in 700 years.
The office of Dean was separated from that of the Archdeacon of Llandaff in November 1843.
The restoration of the Dean's office was the beginning of better times for the cathedral.
The new Dean, William Bruce Knight, was instrumental in bringing about the much-needed restorations.

Enough restoration had been completed to allow the cathedral to be reopened for worship on 16 April 1857.
The see of Gloucester lent their cathedral choir for this service, making it possible to hear choral music in Llandaff Cathedral for the first time since 1691.
The restoration done up to this point was to remove all traces of the Italian temple and to repair damages caused by the attempt to transform the cathedral by Wood.
 Arches with beautiful moulding were hidden by walls, Sedilia were removed from their original positions and reredos had been covered with plaster or hidden with walls.

A meeting was held after the service and a detailed restoration plan was announced at the meeting along with a list for those wishing to donate to the work.
The Prince of Wales (later Edward VII) and the Marquess of Bute were among those who pledged donations sufficient to allow the restoration work to continue immediately.
The cathedral was extensively restored, the tower rebuilt and a spire added.
Much of the restoration work was completed by local architect John Prichard between 1843 and 1869.
A triptych by Dante Gabriel Rossetti was designed for use as a reredos, and a new stained glass window, Shipwreck of St Paul, was designed by Ford Madox Brown.
Sir
During the English Civil War, the cathedral was overrun by Parliamentarian troops. Along with other destruction, the troops seized the books of the cathedral library, taking them to Cardiff Castle, where they were burned along with many copies of the Book of Common Prayer. Among those invited to the castle to warm themselves by the fire on that cold winter day, were the wives of some sequestered clergymen. Also during this time of unrest, a man named Milles, who claimed to be a practising Puritan, appropriated portions of the cathedral for his own gain. Milles set up a tavern in the cathedral, used part of it as a stable, turned the choir area into a pen for his calves and used the font as a trough for his pigs.
The southwest tower suffered major damage in the Great Storm of 1703 and by 1720, was in a state of collapse. The damage to the cathedral was so extensive that the church seriously considered removal of the see to Cardiff in 1717. Between 1720 and 1723 a series of storms proceeded to damage the cathedral further, bringing down sections of the roof as well as other destruction. The collapse of 1723 forced worship services to be confined to the Lady Chapel and closed the western entrance of the cathedral entirely. 
Thirty years after the cathedral roof collapsed, the chapter asked an architect, John Wood, the Elder, to prepare estimates and plans to restore the cathedral. In 1734 work began on a new cathedral, designed by Wood. Wood produced an Italian temple style edifice, working only on the eastern portion of the building, while leaving the remaining western half in ruins. What Wood was trying to build at Llandaff was not Italian, but a recreation of Solomon's Temple.  Another sixteen years passed before the chapter solicited funds to repair the western half of the building. Wood's plans were to replace the western entrance of the cathedral with a tower and rustic porch. No changes were made to the western entrance until Wyatt and Prichard began their work in 1841, when the damage to the western portion of the structure was repaired and all traces of the Italian temple work by Wood had been removed from the cathedral.
During the 19th century the bishop began to reside in Llandaff for the first time in centuries; no bishops of the see resided in Llandaff for almost 300 years. In 1836 there was another unsuccessful attempt to transfer the see—this time to Bristol. After the attempt at transferring the see, the office of Dean was restored to Llandaff; the position had not been filled in 700 years. The office of Dean was separated from that of the Archdeacon of Llandaff in November 1843. The restoration of the Dean's office was the beginning of better times for the cathedral. The new Dean, William Bruce Knight, was instrumental in bringing about the much-needed restorations.
Enough restoration had been completed to allow the cathedral to be reopened for worship on 16 April 1857. The see of Gloucester lent their cathedral choir for this service, making it possible to hear choral music in Llandaff Cathedral for the first time since 1691. The restoration done up to this point was to remove all traces of the Italian temple and to repair damages caused by the attempt to transform the cathedral by Wood.  Arches with beautiful moulding were hidden by walls, Sedilia were removed from their original positions and reredos had been covered with plaster or hidden with walls.
A meeting was held after the service and a detailed restoration plan was announced at the meeting along with a list for those wishing to donate to the work. The Prince of Wales (later Edward VII) and the Marquess of Bute were among those who pledged donations sufficient to allow the restoration work to continue immediately. The cathedral was extensively restored, the tower rebuilt and a spire added. Much of the restoration work was completed by local architect John Prichard between 1843 and 1869. A triptych by Dante Gabriel Rossetti was designed for use as a reredos, and a new stained glass window, Shipwreck of St Paul, was designed by Ford Madox Brown. Sir
Llandaff Cathedral