Possibly a typo in the OCR or even in the original print version. Removing "Miss Tuff", the sentence makes perfect sense, in context of course. "Miss Tuff was a war-time product; the first woman who had ever sat at a desk in a respectable solicitor’s in Milford. A whole revolution was in her single gawky thin earnest person. But the firm had survived the revolution with hardly a jolt,......". We are getting a real overdose of Josephine Tey.

It's very odd phrasing. Is it the complete sentence, with original punctuation? If so, the only way I can read it as an inversion for some effect that escapes me without the context, i.e."Miss Tuff was a whole revolution [i.e., revolutionary] in her single gawky thin earnest person." Moving the complement to the front emphasises it, or alternatively provides continuity with a possible previous mention of the revolution in question. But I still think it sounds odd!

I'm assuming this text is from literature. This sentence seems like it is a characterization of who Miss Tuff was in the past, and that she had upheld that character for a long time. Hence the word, "revolution." A "gawky" person is a way to describe someone who is a bit awkward, even ungraceful. An "earnest" person is a way to describe someone who is serious or extremely dedicated, or diligent.