The origins of the current building date back to 1840 when Bishop Wareing commissioned Augustus Charles Pugin to design a collegiatechapel (1844). The number of worshippers soon outgrew the size of the building and Pugin's son Augustus Welby Northmore Pugin was chosen by Bishop Amhurst to design an extension in order to make the building into a cathedral. This extension came in the form of the current nave which was opened in 1864, dedicated to Our Lady Immaculate and St Thomas of Canterbury.
The cathedral was left in this form until 1955 when it was decided by Bishop Leo Parker that the west end of the cathedral should be extended. This meant that St Andrew's chapel (1825) had to be demolished in order for the development to go ahead.