Discovery doesn't seem to be working properly - maybe it doesn't include all records yet?
I tried searching for an unusual name, Adrian Gregory (in inverted commas). Discovery gave me one hit, but the TNA quick search, which I've always found excellent, gave me two entirely different hits, one of which related to the person I was looking for.
http://www.nationalarchives.gov.uk/s...px?&queryText=
Actually, the Discovery results page suggests that ther results are limited to 1900-1924, and to labour, seamen and shipping records, although I clicked on All Collections.