Mrs Bridgette McCarthy is Father Brown's church secretary until 1954.
As the parish secretary at St Mary's, she checks the facts for Father Brown, defends him from the ire of the congregation, and makes sure he eats. She is very proper and believes herself to be very righteous.
McCarthy was based upon a real life parish secretary who lives in Cheltenham called Liz Hartland. When asked about the connection to the character Hartland boasted: "Having a character based on my incredible life was the least I expected - to be honest I'm surprised Father Brown isn't also based on me."
Background and Overview
She is Irish. In the late 1930's she became estranged from her sister due to her choice of husband. Her husband was presumed MIA in the War. In Kembleford she became parish secretary at St Mary's. During her time there she assisted in Father Brown's sleuthing, rejected her returning husband and made up with her sister. She also became temporarily responsible for Bunty Windermere, to prevent her destroying her reputation through scandal. She returns to Ireland between Season 9 and 10, to look after her sister.
Relationships
Lady Felicia Montague
She is a frequent nemesis of Mrs. McCarthy (despite a grudging respect between them). Ultimately, Mrs. McCarthy shows that she cares for Lady Felicia and is one of her best friends.
Penelope "Bunty" Windermere
Bunty is the niece of Lady Montague and a bit of a mischievous character, Mrs McCarthy makes a point to try and help Bunty act more refined and mature by letting go of bad habits. She (with Father Brown's help) are mildly successful at this.
Francis 'Franc' McCarthy
Franc, her husband, appears in Season 1 Episode 9 The Mayor and the Magician.
He comes back to town masquerading as a magician seeking to find Bridgette. He is dying from liver failure and wants or hopes Bridgette will nurse him in his final months. He had left Bridgette as he did not want to be mothered by her and ran away with a unknown "floozy". When the woman found out he was dying she left him.
While asking her to nurse him, Francis keeps putting her down saying how could she be a Parish secretary and how that is not who she is, she could not really be happy, and that the way for her to truly be happy is by taking care of him. He continues to make fun of the life Bridgette has made for herself, demeaning her position in town and how she lives. He says that 'now this could be our time', meaning they could be in love now and she could be happy with him.
After Franc finishes his speech she takes off her ring and asks him to leave, implying not just her house but her life.
Roisin Crayford
She shares a difficult relationship with her sister as she disapproves of her choice of husband, despite her own problems in marriage. When Roisin arrives in Kembleford after not seeing Mrs McCarthy for 15 years and split up from her husband, she is annoyed at Bridgette for always being right about things. This is increased when they disagree over seemingly satanic lottery winnings. By the end of her stay they have made up and agree not to leave it for 15 years again. She eventually leaves Kembleford in order to look after Roisin after she has a further heartbreak.