Many will remember his epigram about "The curious incident of the cardinal in the night - the cardinal did nothing in the night, that was the curious incident," referring to the Archbishop of Westminster's failure to give any kind of a moral lead on Catholic teaching. As a result of this, and similar cases, Holmes was often consulted on delicate Catholic matters.
Thus, one morning, we were sitting in Baker Street discussing the new Encyclical Humanae Mortis, which had driven Holmes to inject himself with a seven percent solution of "coke" - the scientific name is "Coccopalmerio" - when our servant Mrs Beattie opened the door to admit a man dressed inconspicuously as a South American general.
Our illustrious client.
"Mr Holmes, I need your help," said our client. "A book has been written about, er, a friend of mine, and we need to trace the author in order to, um, pay him homage. The Swiss Guards are already standing by with torture implements."
"I am at your service, Holy Father," replied Holmes (to my gasps of "amazing, Holmes, how did you penetrate his disguise?") "Shall we go to Rome, and make enquiries?"
We took Pope Francis's private jet to Rome, and the flight passed quickly, since our client remained standing throughout the journey, developing new Catholic doctrines "off the cuff": these will one day astound and delight the world. That evening, Holmes and I settled into an apartment in the Vatican. Holmes took out his violin as an aid to concentration and played a haunting arrangement of Stephen Walford's renowned concerto for piano and Balinese nose-flute (with its famous marking "Play whatever the Pope wants").
After two or three minutes the door opened and an African cardinal strode in. "SILENCE!" he bellowed angrily, and threw a book at my companion's head, stunning him slightly.
"... so many noisy popes..." (paragraph 40)
Once I had bandaged his head, Holmes and I made a tour of the building. We were standing outside Cardinal Coccopalmerio's apartment when we heard impassioned cries of "No! Yes! YES! YES! YES!"
"I see that they are working on an answer to the Dubia," I remarked to Holmes. He gave me a funny look that I did not understand, and began to analyse the mystery we were trying to solve.
"Watson, my theory is that the book The Dictator Pope was not written by the real Marcantonio Colonna, as he has been dead since 1584. More likely, it was written by a liberal Catholic, tired of trying to defend the Pope's obvious failings."
"I have an alibi. I am dead."
"Amazing, Holmes. Could it be Spadaro? Ivereigh (no, it's too well-written)? Massimo Faggioli? James Martin (no, there's no obsession with homosexuality)? Rosica?"
"These are deep matters, Watson, and perhaps I am wrong. But the case presents interesting features. For example, why is the book produced only electronically, and not on paper? Did Cardinal Baldisseri steal all the printed copies?"
Putting on his liturgical deer-stalker, Holmes led me into Mass, where Cardinal Paradigm was going to preach about Parolin Shifts in Amoris Laetitia. To me it sounded like complete heresy, but then Homes explained that this sort of nonsense was necessary if a cardinal wished to be considered papabile, and Cardinal Paradigm probably didn't believe half of what he was saying.
"We have found the man who stole the Pope's vestments" announced Holmes.
To be continued?