p. 286, y-axis:
??? Design Conference
1st Flight of Prototype
Delivery of 1st production
Delivery of 1st X ???
X-axis at top:
Mosquito
X1
X2
X3 (Spitfire???)
X4
Typhoon (vertical from "Delivery of 1st Production" level)
Whirlwind? (vertical line)
Meteor (the diagonal that meet another line at the top with the "59")
X7
Vampire
As the lines start up, bottom is Vampire, second to bottom is Whirlwind, above that might be Spitfire?