Augustus Welby Pugin was the son of a French émigré who settled in England and became an architectural draughtsman. Under the tuition of his father, Augustus Welby also became a fluent draughtsman and by the 1830s, was widely employed in church design. He also wrote a number of books on architecture. Following his reception into the Catholic Church, he lost much work but also received many commissions to design Catholic churches, the first being St. Mary's in Derby.

Among others he designed are the cathedrals at Birmingham, Southwark, Nottingham and Killarney, also churches at Manchester, Oxford, Preston, Rugby, Northampton, Stoke, Stockton and many others. There were nearly always restrictions on his designs because of the shortage of money and St. Mary's Cathedral was no exception, but the church at Cheadle, his masterpiece, was paid for by the Earl of Shrewsbury and therefore was not restricted in any way. Pugin is now very well known because of the magnificent worked that he did on the Houses of Parliament.

The Welby in his name was his mother's maiden name which he seemed to prefer as all his correspondence about St. Mary's are signed A. Welby Pugin. He was known to work from sunrise until midnight and it was his obsession with work that caused his mental breakdown. In 1852, after a few weeks in an insane asylum, he was taken home where he died shortly after of an epileptic fit in September, at the age of 40. It is said that the work he did in his short lifetime would have taken other architects a hundred years to complete.

The difficulty he experienced in procuring metalwork of sufficiently high standard for the buildings he designed led to the formation of the firm of Messrs John Hardman & Co. After many failures, Pugin and Hardman succeeded in producing the top quality work they sought.

Another protégé was George Myers who was successfully connected with all of Pugin's larger works and it is recorded that all the carvings in St. Mary's are his work. Pugin designed the Great East Window in St. Mary's, also the windows in the Lady Chapel and Blessed Sacrament Chapel, and to carry out his designs, he commissioned William Wailes who had premises in Bath Lane, Newcastle. Through his work for St. Mary's, Wailes achieved some renown as a stained-glass maker and examples of his work are to be found in many churches.