Barton became the housekeeper to Charles Montagu following the death of his wife in 1698. There was much contemporary gossip about their relationship being sexual, and thinly disguised accusations appeared in print.
Delariviere Manley's
Memoirs of 1710 featured a character called Bartica who was widely taken to represent Barton. Montagu, by then
Earl of Halifax, died of an inflammation of the lungs in May 1715. His will contained two
codicils: the first dated 12 April 1706, left the sum of £3000 and all his jewels to Barton; a second dated 1 February 1713 left her an additional £5000 plus his interest in the rangership of
Bushey Park and his manor of Apscourt in
Surrey to pay for the repairs to Bushey Lodge. On 30 August, however, he revoked the first codicil and begged his executor, his nephew George Montagu, not to make a dispute over her legacies. Montagu wrote that these bequests were "as a token of the sincere love, affection and esteem, I have long had for her person, and as a small recompense for the pleasure and happiness I have had in her conversation". Halifax's official life defended Barton against accusations that she might have been sexually involved with him, stating:as this Lady was young, beautiful and gay, so those that were given to censure, pass'd a Judgment upon her which she no Ways merited, since she was a Woman of strict Honour and Virtue; and tho' she might be agreeable to his Lordship in every Particular, that noble Peer's Complaisance to her, proceeded wholly from the great Esteem he had for her Wit and most exquisite Understanding.Based on the generosity of the bequest, astronomer
John Flamsteed wrote, apparently sarcastically and spitefully, that Barton must have "
excellent conversation". ==Marriage==