Small Blue-Green World

Welcome to a Small Blue-Green World, an independent IT consultancy specializing in technical authoring and editing services, IT security awareness and training and IT security research. We work with leading IT security specialists and professionals, mainstream publishing houses and technical authors to educate and inform the public and those involved in IT security in the enterprise as regards best practice.

Papers and articles on computer security issues written by David Harley can be found at or via Geek Peninsula.

David Harley launched Small Blue-Green World in April 2006. when he left  the UK’s National Health Service, where he was manager of the National Health Service’s Threat Assessment Centre, in order to focus on writing, publishing and consultancy. Up until December 2018 he worked closely with ESET, his primary client for nearly 12 years.

David has been researching and writing about malicious software and other security issues since the end of the 1980s. While specializing in virus and email abuse management, he also holds qualifications in general security management, service management (ITIL), security auditing and medical informatics.

He is a former director of AMTSO (the Anti-malware Testing Standards Organization), and for some years ran an independent blog site focused on independent commentary on security product testing. He also maintained the Mac Virus web site and a number of independent blogs and resources.

If you’re looking for the musical and other extracurricular stuff that was here for a while, it’s now at David Harley’s Songs or David Harley’s Verse


This is the new, revamped, official Small Blue-Green World site, maintained by David and Judith Harley. The photograph used as the site banner shows a the sculpture of Pi, by Rawleigh Clay,  which is located in the Botanic Garden in Wales and the site’s name comes from the Hitch-Hiker’s Guide to the Galaxy, by the late and much-missed Douglas Adams.