A recent correspondent who wishes to remain anonymous put me on the trail of Bonomi's sponsor the gambler and occultist Lord Kilmorey (also known as 'Black Jack' Needham). Black Jack became infamous for eloping with Priscilla Hoste who although once his young ward, became the love of his life. Although much younger than he, his love appears to have been reciprocated but the scandal of the affair or the strangeness of his arcane rituals (which had seen his separation from two previous wives) proved too much of a strain on her and she died. Whether she expired during one of their love rituals or not, she certainly passed on prematurely of an 'exploded heart' - cementing the reputation of Black Jack as a demon lover.
Wracked with grief and guilt at his loss, he consulted with his fellow occultist Bonomi in the hope of finding a way to re-animate the dead girl or at least to be able communicate with her. Bonomi instructed the architect Henry Edward Kendall in the construction of an Egyptian mausoleum and covered it with heiroglyphs dedicating it to Osiris concerning the journey of the soul through the afterlife. The mausoleum was initially constructed in Brompton Cemetery near the Courtoy tomb described beneath but extraordinarily, the whole edifice was subsequently 'moved' - first to Chertsey and then to the grounds of Gordon House in Isleworth where it stood hidden for many years. Whether this movement was by means of horse and cart or was a successful example of Bonomi and Warner's teleportation techniques, I leave you to decide.
It has been speculated that the mausoleum was intended to be a 'master' teleportation chamber which somehow controlled the grid of other chambers located in each of the cemeteries which ring London. Certainly Black Jack had a hidden tunnel built linking it to Gordon House and was said to dress in white, lay in a coffin and be wheeled by his servants through the tunnel to be left with the deceased Priscilla. Whether he did this so he could attempt to communicate with his dead love or to teleport on a discreet journey into town, who now knows?