Baron von Eisenger

In the novel Cat Among the Pigeons, Baron von Eisenger is the father of Hedwig. He had written to Mrs Bulstode to request to take his daughter out for a performance of the opera Tristan and Isolde. In Mrs Bulstrode's letter of reply she acceded to the request, noting that was an occasion when "Hellstern" was playing the part of Isolda. This suggests that Hedwig might have a sister named "Hellstern" (although this is not a common German name). She might even have been a former student.