Months after reading What Maisie Knew it has dawned on me that Ida plays a key role in the ending of the novel. We hear nothing of her in the final chapters but her last actions are strange indeed.
From the first Ida has been portrayed in an appalling light, particularly in her role as a mother. The divorce court deemed her an unsuitable parent, awarding sole custody to Beale Farange, a man who has nothing whatever to recommend him as a father or a husband.
And yet, once Maisie has lost both parents and is bound for France, Ida seeks her out at Folkestone intending to offer her a parting ten pounds, as Ida herself is preparing (we suppose) to emigrate to South Africa - as far from Europe and Maisie as possible. Even stranger, Ida seeks out sacked Mrs Wix and gives her much encouragement as Maisie's future guardian and the ten pounds, although Ida had long withheld even Mrs Wix's paltry wages before telling her to "Bundle."
Since Ida has long fought a war with ex husband Beale, it seems plausible that she is firing a salvo at estranged Sir Claude, who is ultimately left alone with the dreadful Mrs Beale. But as collateral damage, Maisie is left with poor, clueless but decent Mrs Wix and her ten pounds. Doesn't the novel ends with what Ida knew?