The Mk. VII Churchill tanks used the QF 75 mm, which fired the American 75 mm shell, and it had considerable trouble penetrating the frontal and side armor of a Tiger. With a muzzle velocity of 2050 ft/s and 1300 kJ muzzle energy, the 75mm AP shell could only penetrate 68 mm of rolled homogeneous armor at a 30* angle. The Tiger I had 100 mm of frontal armor, and that was flat. The Tiger II had an upper hull plate of 150 and was sloped back at 40* (lower plate: 100 mm at 40*).
Words and numbers, Lady Darjeeling's Churchill would have had a very slim chance of knocking out that Tiger II.
