Personally me choice would be to avoid anything that encourages legal compliance rather than 'best practice'. In my career learning from accidents that others have suffered has been a huge learning area. Have you considered David Eves book published by IOSH? Or any of the several books by Andrew Hopkins, or by Trevor Kletz (the latter being mainly pocess industry based)?
Most of the other IOSH books are very good value I believe - choose one that links to your interests or an area you wish to learn more about.
Or get something for nothing - for example the US National Commission on Deepwarer Horizon which covers all the regulatory and political failings as well as those by the organisations directly involved. Well worth much study and freely downloadable, as is the BP internal investigation which is a good model of how to set up a really major one (that doesn't mean I think it covers everything relevant - rather that it explains what its purpose is and does that pretty well).

Thank you to those of you who sent me suggestions by PM.