Thanks for the review, and I'm glad you think people need to buy the book.
Perhaps I could just point out one or two inaccuracies in your review. First of all, I have made it very clear that the natural passage in Ayleburn Mine Cave is 1,700m long. I have not included the mine level at all in the length or depth stated for this cave. The old mine entrance has been sealed because the current owners, Shepherds Solid Fuel, have resumed quarrying/mining operations.
Quite a few of the caves are in limestone and most are definitely more than ten metres! However, what first inspired me to write a book about Northumberland's caves was the fascinating history and folklore associated with so many of the shorter caves, which is why you will find far more written about the short caves than you might usually expect in a caving guidebook. There are also detailed descriptions of the longer caving trips, such as Hartleycleugh Quarry Cave (a glorious 383m limestone cave with a long duck halfway along) and Elpha Green Caves (260m of wonderfully-decorated stream passage). All written in a very interesting and entertaining way, I hope.
Chris Scaife