The Great Fire of London started around 12.15 am on September 2 1666, destroying nearly 90% of the houses. It followed on from a devastating outbreak of bubonic plague the year before.
As per usual, with a superstitious population, it was deemed that someone had to be to blame – French and Dutch immigrants being high on the list. Astrologer William Lilly was hauled in for questioning since he had predicted it 12 years earlier in a heavily disguised, codified drawing which according to interpretation pointed to the day in question though timed five hours later. See: http://www.skyscript.co.uk/fire.html
It isn’t known how he arrived at his conclusion.
The actual chart has Jupiter exactly conjunct a Pisces Midheaven opposition Sun square Pluto in Gemini – so undoubtedly a huge upsurge of energy. 9/11 also had Jupiter conjunct the MC, so clearly Jupiter not in its beneficial mode. And 9/11 also had a Virgo Sun square Pluto (tied into Saturn) suggesting a powerful event.
The Mars in Scorpio of the Great Fire was heavily aspected in trine to Jupiter and sextiling onto a paranoid Saturn Neptune in Capricorn, as well as being square Uranus – so destructive and explosive, causing panic and confusion. With an Air Grand Trine of Uranus trine Pluto trine Venus in Libra. 9/11 also had an Air Grand Trine of Uranus, Mercury, Saturn, as did the Iraq War of Saturn, Moon, Venus. Both of them were more obviously Air-borne disasters, but I suppose Fire does need air to spread. There are no Fire planets at all in the Great Fire chart.
Lilly probably worked with Eclipse and Ingress charts. The Aries Ingress for 1966 had a brutal Mars (28 Virgo) Moon opposition Venus square Pluto (25 Gemini). The Capricorn 1965 Ingress had an exact Mars square Pluto at 26 degrees – so it would raise flags for the months following. And the Cancer 1666 Ingress had the Mars square Pluto tied into Jupiter and the Sun.
The July 1666 Solar Eclipse had Uranus closely conjunct the Descendant/chart axis, making it a powerful significator of a disruptive event’ and the Cancer New Moon was square Mars and opposition Saturn (conjunct Neptune) – accident prone; and the Lunar Eclipse of June 1666 had the Full Moon at 25 Sag/Gemini with Pluto at 26 Gemini squaring onto Jupiter. Ebertin says of Jupiter Pluto in its most negative mode : “ Loss of social standing and one’s wealth. The misfortune to lose everything.”
Lilly evidently took London to be a 14 degree Gemini place. Looking at London crisis events I’m not sure I wouldn’t make it a later degree Gemini. The London Blitz of 1940 started with Neptune at 24 Virgo; the Brixton Riots of 1981 had Neptune at 24 Sagittarius. The 2008 Lehman collapse which caused a meltdown in the City of London had Sun 23 Virgo opposition Uranus 20 Pisces square Pluto at 28 Sagittarius. The Great Fire had Pluto at 28 Gemini. So last decan of Gemini seems more likely.