Short answers, pulled from the story.
John Castaing began listing commodity prices at Jonathan's Coffee House in London in 1698. This informal activity marked the earliest evidence of organized trading in marketable securities within the city.
A clutch of incendiary bombs hit the Exchange floor during the night of the 29th of December 1940 starting one of London's greatest fires. Trading dropped drastically as most activity moved over the phone to reduce injury risks while the Exchange remained open except for one day in 1945 following damage from a V-2 rocket.
Over one thousand three hundred large companies from sixty countries trade on the Main Market today. These companies include those tracked by the FTSE 100 Index which measures movements of the one hundred most highly capitalized British companies listed there.
The Deutsche Börse merger announced on the 3rd of May 2000 ultimately fell through without completion. The text does not specify the reason for this failure but notes that Borsa Italiana S.p.A. terms were agreed upon later creating a leading diversified exchange group named London Stock Exchange Group.
Trading sessions run from 08:00 to 16:30 local time excluding Saturdays Sundays and declared holidays. Continuous trading operates until 16:30 followed by closing auction period ending at 16:35 with order maintenance extending from 16:35 to 17:00 before trade reporting resumes 17:00 to 17:15.