In preparation for AIB I have been searching around for whatever literature I feel might be useful for 'swotting up' purposes. I wasn't sure whether this was going to be useful, but bought it anyway, and am quite pleased with it.
As you would probably expect, the book gives details of the assets, structure and specifications of all three branches of the armed forces. There is also a 'top down' explanation of the command structures (starting with the Queen, Government, MoD, Defence Council etc), different groups (JRRF, NATO etc) that the UK forms, as well as current operations and a whole host of facts and figures.
As an RM applicant, I was slightly disappointed with the three and a half pages dedicated to the Royal Marines. The structure is explained quite well, but nothing is said about what equipment they have at their disposal, and whilst most equipment is hiding in the RAF (helicopters) or Army (weapons) sections I could not find anything in the whole book about the Viking or Warthog, or anything more than the briefest mention of landing craft in the Navy section.
However, there are a couple of extras that are a bit of a bonus, including the quotes at the end of the book; my personal favourite is "If you can keep your head when all about you are losing theirs - you may have missed something very important." (Royal Marine - Bagram Airfield 2002)
In all, if you are preparing for selection (particularly officer selection) for any branch of the armed forces I would say it is almost essential reading as it gives a very comprehensive overview of the entire UK Defence Strategy. However, only four stars awarded due to the lack of equipment details for the Royal Marines.