There's a pretty long podcast where a guy delves into why humans "like" to watch other humans suffer (we do it virtually now with movies depicting it rather than gathering at the gallows). He digs into a lot of historical stuff regarding executions. Also mentions a book compiled from the diary of an executioner --- called The Faithful Executioner. Executioner was a job that paid pretty good but marked you as untouchable like the tax collector. It stayed as a family vocation passed down from one gen to the next.
https://www.amazon.com/Faithful-Executioner-Turbulent-Sixteenth-Century-ebook/dp/B0096MTBO4
There's an excellent book about this (according to my spouse): The Faithful Executioner: Life and Death, Honor and Shame in the Turbulent Sixteenth Century. It's from primary sources, namely an executioner writing about his life.
Good time to plug an episode we did on the Sanson Family, the executioners of Paris for 200 years, including through the French Revolution. If you've got a dozen hours and reading is more your style, his memoirs are in two parts. Volume I and Volume II. Those are primary sources from the last Sanson himself and include several different Sansons, so it's the best you'll get in terms of what it was like to live as an executioner family.
If you'd rather hear from a professional historian (I'm not quite that yet) but still get lots of primary sources, The Faithful Executioner by Joel Harrington about the Executioner of Hof is a good one, and includes his journals.
Sorry if that's more than expected. My master's thesis I'm currently working on is the psychological state of executioners in early modern Europe, so it excites me a lot.
Okay, well, I've found one possible way for you.
I believe the book that you're mentioning would be Rev. Thomas Baker, 1832-1867 : personal diary and collected papers.Baker, Thomas, 1832-1867, published in 1982. This particular volume is in the State Library of New South Wales, Australia. There's another volume in the Camden Theological Library as well.
Unfortunately, if you're not currently in NSW, it might be a bit difficult to get your hands on it. While the NSW library does offer interlibrary loans, it doesn't apply to items in the Mitchell Library collections, as they are restricted to on-site browsing only. The volume in the Camden library is restricted to staff access as well. So it might be that you would need to find a way to go down.
As for other interesting diaries, I typically recommend The Faithful Executioner, which I feel has a great writeup on the historical and cultural context in which all the stuff took place, plus an absolutely fascinating topic it covers. Another memoir I think gives a really great story is No Feast Lasts Forever from Madame Wellington Koo, which provides a great look at many major 20th century events from a pretty unique perspective. Another one, from a more 'everyman' perspective, is Intimacy and Terror: Soviet Diaries of the 1930s .
Hope this is of some help!