Second part of a post; the first part is here, or directly below this one.
Isabella and Edward II's son Edward of Windsor sailed from Dover on 12 September 1325 and paid homage to his uncle Charles IV for Gascony and Ponthieu at Vincennes twelve days later. The boy turned thirteen on 13 November 1325. Edward of Windsor's presence in France was a key factor in Isabella's decision not to return to her husband: with their son the king's heir, the future king of England, under her control, she held a vitally important bargaining chip, and used her adolescent son as a weapon against her husband. As I've pointed out before, although Edward II's decision to send his heir to France in September 1325 appears with hindsight to have been an incredibly foolish decision, it wasn't really; Edward had painted himself into a corner where all possible options available to him were fraught with risk, and after weeks of agonising sending his son away must have seemed, and in fact probably was, the least dangerous course of action.
Edward of Windsor was accompanied to France by, among others, Walter Stapeldon, bishop of Exeter and treasurer of England (who had founded Exeter College at Oxford in 1314). Isabella loathed Stapeldon, believing that along with Hugh Despenser the Younger he had been instrumental in persuading her husband to confiscate her lands in September 1324. Stapeldon came to believe, whether correctly or not, that there were people at the French court who intended to harm him, and fled back to England disguised as a common traveller. He was back by late October 1325. Historian F. D. Blackley suggested a few decades ago that Walter Stapeldon was the immediate cause of Isabella's decision; he had been authorised to pay the queen's expenses, but only for her return journey to England. As he fled from Paris before he gave her the money, this may have forced her into making the decision whether to return to England and the dominance of the hated Despensers, or remain in France. A furious Isabella sent Stapeldon a sharply-worded letter on 8 December accusing him of being of Hugh Despenser’s 'accord' and more obedient to him than to her. She also accused him of dishonouring Edward II, Charles IV and herself.
According to the Vita Edwardi Secundi, Charles IV, "not wishing to seem to detain her said 'The queen has come of her will, and may freely return if she so wishes. But if she prefers to remain in these parts, she is my sister, and I will not detain her.'" (Vita, ed. Denholm-Young, p. 143.) One modern writer has claimed "There is no incontrovertible evidence to prove that Isabella and her brother King Charles had worked behind the scenes to secure her son's presence in France and simultaneously prevent her own return to England, but it is by far the most likely conclusion in the light of their wholly compatible interests and the immediate support Charles gave her once she had made her feelings known." The French king's speech above is then cited as evidence of this support. Charles IV's role in the events of 1325/26 is intriguing and often ignored, but quite how anyone gets from his seemingly rather grudging remark 'I won't expel my sister from my kingdom, but she's also free to go back to England if she wants to' to 'Charles had been supporting Isabella behind the scenes for years to help her bring down her husband' frankly is beyond me. In the same way, I really don't get how Isabella's speech 'an intruder has come between my husband and myself, and I won't return to my husband until he is removed' has come to be interpreted as 'I hate my husband and am defying and rebelling against him with my beloved Roger at my side'. This is all too typical of much modern writing about Isabella; frankly it's little more than fiction with her name attached to it. There's a tendency to see secret plots and cunning conspiracies and long-term, Europe-wide strategies against Edward II everywhere, which makes a good story; a better story than people just muddling through and making short-term decisions rather than following a series of complicated, high-risk steps over a period of years with the aim of bringing Edward II down. A good story is a good story, but that doesn't necessarily make it true. It's so tempting to look at where Isabella ended up in 1326/27 and assume that she'd been planning her husband's downfall since August 1323 when she supposedly helped Roger Mortimer escape from the Tower, or since 1322 when Hugh Despenser returned to England and became her enemy, or even since November 1312 when her son was born and it occurred to her that she could wield more power as the mother of the king than as the wife of the king. In reality, however, it's even possible that Edward II's deposition wasn't intended or mooted until as late as Christmas 1326, after the executions of the Despensers and when it was clear that his position as king had become untenable.
Edward II, having heard of Isabella's refusal return to him, cut off her expenses in mid-November 1325, and, short of funds, the queen was forced to borrow 1000 Paris livres from Charles IV on 31 December. This was the equivalent of only £200 sterling, less than a month's income for Isabella even on the reduced amount imposed on her in September 1324 when Edward confiscated her lands and gave her an income from the Exchequer, and was a loan, not a gift – hardly a sign of her brother’s great favour towards her, as it has sometimes been interpreted. Many of Isabella's servants, whom she could no longer afford to pay, went back to England, from late November 1325 to January 1326: they're mentioned in Edward II's chamber account when they received money for their travel and other expenses from the king on their return.
Edward II wrote his last-ever letter to Isabella on 1 December 1325, ordering her home and claiming that he was suffering badly from her 'so very long absence'. Unfortunately, he also went into endlessly long and tedious justifications for Hugh Despenser the Younger's behaviour, which must have irritated Isabella immensely. He did the same thing in letters to his son Edward of Windsor, Charles IV and numerous French magnates and bishops, and before the parliament which began at Westminster - the last one he ever held - on 18 November 1325. Faced with the painful realisation of her husband's priorities and his utter refusal to take her seriously and to send Hugh away from him, Isabella was left with no other choice but to remain in France in November 1325 and, not long afterwards, to ally herself with the English Contrariants on the Continent, led by Roger Mortimer, the men who could help her gain the revenge she had sworn on Hugh Despenser for destroying her marriage.