This isn't a bad book, but I think it could be much better. For one thing, I think a couple of maps would have helped a lot to explain where the various naval battles were taking place, and to show the progress of the fire. In the latter case, a map might be unnecessary if you are familiar with London's geography, which I am not (especially the 17th century version of London).
I also found the author to be rather vague about the timing of the fire. We first hear of it when a message is sent to the fleet, saying, in effect, "London is burning! Come quickly!" The next chapter begins with "A few days earlier", but never actually tells us the date that the fire started. The rest of the chronology is "later that day", "the next night", "on Wednesday", and so on. I suppose it doesn't really matter, but I think it would have brought the story into focus a little more sharply if the author had actually said, "September 2" at the start of it all.
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In addition, I wonder about some of the terminology. I was under the impression that a frigate was a specific type of naval vessel, but the author describes virtually every line-of-battle ship as a frigate, even first-rate ships. This might be a proper use of the term in the 17th century, but it left me wondering about the accuracy of other items in the description.
Finally, I think that there are some characters who are mentioned but not developed sufficiently, such as most of the common folk. However, even principal characters like Rochester and Monck are rather vague.
So, no show-stoppers for anyone who is looking to learn a bit more about this period, but not really a compelling book, either. It was "OK", and the two-star rating suggests.