Rav Kook Ate Manischewitz Matzah
According to this (Hebrew) article from Musaf Shabbat by Rabbi Prof. Neriyah Gotel, Rav Kook was an enthusiastic consumer of machine-made Manischewitz matzah while he was in London during WW I. The article describes the different versions of a letter by Rav Kook that were published in different editions of Igrot Ha-Ra’ayah, one that includes explicit praise and description of using machine-made matzah, and the other that doesn’t seem to make much sense since it was heavily edited.
See this post by Menachem Butler for references to literature on machine-made matzah. My custom is to use machine-made shemurah matzah for the mitzvah of eating matzah at the seder whenever it is available.

April 24th, 2011 at 11:41 am
The big non-chasidic Rabonim of the previous generations were makpid to eat machine matza. R’Aryeh Levin (R’ Elyashiv’s father-in-law) only ate machine matza.
In the Mishpacha there is an interesting article about Rav Kook and the usage of sesame oil on Pesach
April 27th, 2011 at 8:12 am
In a special edition of the Torah journal HaPardes 11:12 (March, 1938), dedicated to the 50th anniversary of the Manischewitz Co., Rav Kook is among over 100 Rabbis who signed a letter endorsing the kashrut of the company.
April 28th, 2011 at 11:38 am
I recall when I was in the yeshiva, that Rav Tzvi Yehudah Hacohen Kook promoted machine matzah. There was a local machine bakery whose name escapes me where he and other rabbanim would bake their matzot. I think it was in Bayit V’gan. I never witnessed this myself, but it was pretty widely known in the yeshiva and I think it was published in one of the Sihot Rav Tzvi Yehuda transcribed by Rav Aviner. This would all be consistent with his father’s approach.