Chris Stoakes trained as a solicitor at Freshfields ( one of the "magic circle" City law firms), was marketing partners in a medium-sized City firm, and is now Head of Legal Training at Lovells (another very big one). In this the 2008/09 second edition, which seems to have been updated following the event of the "credit crunch" in early 2008 (references to sub-prime mortgages, for example), he provides an overview, a context and an often humorous analogy for just about every financial transaction in "the City", including the insurance market. The book is based on a series of training sessions that he has delivered over the years.
I came at this as a reasonably well informed outsider (I have never worked in the City of London, and probably never will) and found this is an excellent book to improve on my broad understanding of the financial markets. Whether it would be right for you will depend on how sophisticated your current understanding is. Stoakes places his book as follows: he starts by saying "I've had to cut corners, leave things out and tell a few fibs in the interests of getting the message across quickly and simply". At the end, under "Where Next?" he recommends The Economist's books on The City, Wall Street and "The Financial Markets" - written by Richard Roberts and Marc Levinson respectively - as "the next step up". He also gives specific recommendations for particular areas, such as Finance & banking, Investment Banking, Commercial banking, Economics, Risk etc.
If you want to be able to differentiate senior debt from junior or subordinated debt, know the principle of mezzanine debt, understand the difference between a merchant and an investment bank, or understand the difference between LIBOR and the base rate, this is the book for you. For my own purposes I see little need to delve deeper, although I may well read Stoakes' other book, "All you need to know about Commercial Awareness" in due course.