During the Age of Romance people liked to build artificial ruins. They can be found in parks and castle grounds all over England, France, Germany, Poland, Italy, and other countries. In this period such artificially decayed artifacts were regarded as picturesque and suffused with the atmosphere of former times.
Another key feature of the Romantic Age is the Gothic novel as represented by authors like Mary Shelley, Ann Radcliffe, Horace Walpole, and many others.
In TAB Mofftiss keep playing with elements of romance and Gothic novel. Even the cemetery in the 2nd modern scene quickly turns into a Gothic stage design, complete with dramatic gravestones, a rotten coffin, and a decayed body dressed in ragged finery. The scene is clearly not real and is preceded by Moriarty’s comment:
“Is this silly enough for you yet? Gothic enough? Mad enough, even for you? It
doesn’t make sense, Sherlock, because it’s not real. None of it.”
Every time a cemetery is mentioned in the show, it has a very Gothic quality and is connected to something that is fake or unreal.
There’s the blind greenhouse in Kew Gardens and the leaning tomb in Hampstead
Mary Morstan was stillborn in October 1972. Her gravestone is in
Chiswick Cemetery where – five years ago – you acquired her name and date of birth and
thereafter her identity. (HLV)
But what does it mean for TFP? Well, here we get the real ruins of a manor house, surrounded by an artificial cemetery. Can there be anything more Gothic?
MYCROFT: The ancestral home, where there was always honey for tea and Sherlock played among the funny gravestones.
JOHN: Funny how?
MYCROFT: They weren’t real. The dates were all wrong.
SHERLOCK: The wrong dates. She used the wrong dates on the gravestones as the key to the
cipher and the cipher was the
A cipher consisting of wrong dates on gravestones standing on (probably) fake graves next to the ancestral home? This is very Gothic. The same goes for the burnt down house itself which is strongly reminiscent of Thornfield Hall in Jane Eyre and Manderley in Rebecca, both of which can be regarded as standing in the tradition of the Gothic novel. (Eurus also reflects the Victorian image of the “madwoman in the attic” as discussed by Gilbert and Gubar but this would deserve its own post).
Therefore the house and the cemetery in TFP are echoes of echoes of the Gothic. And as such they are completely in accordance with the atmosphere of TAB. I leave you to your deductions.