Triumph Toledo brake master cylinder

This table from the  Girling applications catalogue shows that the RHD Toledo was fitted with master cylinder 64066137 between January and April 1971, and 64066252 from May 1971 onwards.

Curiously this chart from the Girling parts index shows that 64066137 is 0.7″ bore whilst 64066252 is 5/8″ bore whilst the wheel cylinders remained the same. My September ’71 car actually came with a 0.7″ bore master cylinder, which according to that chart, should have been 5/8″ by that time.