The file consists of correspondence, sent (and received) by the Engineer to the Humber Conservancy Board (Arthur Ernest Butterfield), to/from various suppliers and contractors on the subject of repair and maintenance work required by the motor launch 'Observer'. This includes correspondence with Daimler Company Limited, Coventry, regarding repairs to the launch’s engine, and a specification (dated 23 June 1915) outlining work required.

Further correspondence is concerned with the launch's crew (their working conditions and terms of employment), and proposals regarding the sale of the launch by the Conservancy.

The file also includes extracts and summaries from the log of the 'Observer' and returns of the forms 'Stores Required (Form A). Further papers received from the Clerk’s Department, dated 17 July 1917, are concerned with the motor launch 'Alert'.