In the novel N or M?, Inspector Brassey is an English police officer, presumably of the Leahampton police who testified at the inquest into the death of the Polish refugee Vanda Polonska.
In his testimony, Brassey explained why the relatives of Polonska had not come forward at the inquest. Brassey said that Polonska's two known relatives were being detained under the Defence of the Realm Act for an offence in connection with a Naval dockyard. Apparently the two had posed as refugees to come to England and had then immediately tried to obtain employment near a Naval base.
According to Brassey, the authorities looked upon the family with suspicion. They had had a larger sum of money in their possession than could be accounted for. As for Polonska herself, Brassey said that nothing was actually known about her except that her sentiments were believed to have been anti-British. It was possible that she also had been an enemy agent, and that her pretended stupidity was assumed.