How to retrieve original pdf stored as MySQL mediumblob?
In line with my assumption and Isaac's suggestion the only solution was to be able to speak to one of the software developers. It transpires that the documents have been zipped using an third-party library as well as the header being removed before then being stored in the database. The third-party library used is version 2.0.50727 of Chilkat, available from www.chilkatsoft.com. That version no longer appears to be available, but hopefully at least one of the later versions may do the job. Thanks again for everyone's input and assistance.