It's chilling to see this form, knowing how many men who filled it out discovered later that it'd been an involuntary suicide letter, condemning them to a horrible death in an unnecessary war.
That aside, a few details do stand out, almost a century later, about how things were done back then:
First, that this was an application for a "temporary" commission, one to last only until the end of the war.
Second, the question about whether he cd ride a horse: a relic from an earlier day and a different kind of war.*
Third, the curious question (v. high up on the list) asking for assurance that he's "of pure European descent". I assume this requirement is to screen out 'half-castes', as they were called in those days -- British citizens who had a parent or grandparent among the colonial peoples the British had conquered and subjugated. I know that in such a deeply racist society as prewar (and postwar) Britain such folk faced all kinds of societal ostracizing, but had not realized their background precluded their serving as officers as well.
Still, a remarkable document. A good example of how context and foreknowledge affects the effect of what we read and see, how something as simple as a form letter can be weighted with sinister forboding when we know what all awaited him in the next few years.
*though in point of fact being able to ride in training camp turned out to be just about the only thing Tolkien enjoyed about his military service.
UPDATE (Tues. Jan. 10th):
I hadn't realized that this link originated with Mike Foster, whom I shd have credited. Sorry Mike! --JDR