In 1823, Peter Baines was made co-adjutor which also brought him the title of Bishop of Siga; he succeeded Bishop Collingbridge to the post of Vicar Apostolic of the Western District in 1830. He was a popular preacher and it was said of him at the time that a church which was nearly empty when preachers of inferior mark occupied it, was crowded when Father Baines was announced as the orator.
He preached regularly at the Orchard Street chapel, attracting crowds from congregations beyond his own, as illustrated by these remarks from John Skinner, the Anglican Vicar of Camerton, in his ‘Journal of a Somerset Rector’:
Having understood that the new Catholic Bishop, Mr Baines, was to preach on Corpus Christi, I accompanied Mr Haggard and my brother Russell to the Chapel in Bath after breakfast. I shall not attempt a description of the ceremonies employed, sufficient is it to say that no acting during the time the Chapel was a theatre could exceed what we then witnessed. With regard to the subject of Mr Baines’ discourse, delivered, I must do him the credit to say, in a very impressive manner, the delusive turn respecting corporeal and spiritual by no means benefitted his argument with men of reading or reflection. I am speaking of the Protestant part of his hearers, who appeared to be very numerous, considering the admission to the Chapel was two shillings apiece for those of a different community.
Following his appointment, he organised the purchase of Prior Park Mansion and moved there to supervise its conversion to a Catholic University. His sudden death in 1843 at the age of just 56 was sadly mourned and during the two-day lying in state, upwards of thirteen thousand people of all denominations travelled to Prior Park to pass round the catafalque.