Here's a curiosity from the City of London CID records. It seems that Monro saw fit to issue a warning about the activities of a company known as "H. Williams & Co," based in Fleet Street. The company sought to turn the affair to its advantage by portraying itself as the aggrieved party, and issued this advertising handbill, which opens with a very politically incorrect description of Monro, and is adorned with a cartoon showing him steaming open a letter. Simon Wood kindly sent me a British Library catalogue entry for a copy of this handbill, which has a handwritten date of 14 October 1886.
This excerpt from the Sheffield and Rotherham Independent of 14 August 1886 fills in some of the background of the affair, and reveals that the company in question was being run by two of the men who had been involved in the notorious Turf Fraud Scandal of 1877: http://www.met.police.uk/history/turf_fraud.htm