The hardback edition of "The Gaol: The Story of Newgate - London's Most Notorious Prison" by Kelly Grove is available from Amazon for £17.50 which is a 30% discount on the RRP.
Click on the link above to go to the correct page at Amazon where you can read more, where you can find the New & Used section and where you can buy the book if you want to. If you buy the book from Amazon (and not the New and Used Section) whilst it is above £15 you can get free delivery if you choose then Super Saver Delivery option.
Please note that the information above is correct at the time of writing but that price and availability do sometimes change at Amazon.