Ron Embleton was not a prolific paperback cover artist, but his cover work pre-dates the painted strips he produced for comics by some years. The subject matter may be straight out of the pulps in most cases, but they show Embleton's confidence in the use of colour even when the artist was still only in his early twenties (in fact, the earliest known cover listed here dates from around the age of 18/19, but I don't have a scan).
Martin & Reid
Carter, Tex * Trouble Buster * c.1949.
Cherry Tree (Kemsley Newspapers)
400 Long, Frank Belknap * John Carstairs, Space Detective * nd (Sep 1951), 192pp, 1/6.
291 Gruber, Frank * The Scarlet Feather * nd (Dec 1951), 192pp, 1/6.
409 Hubbard, L. Ron * Typewriter in the Sky (and Fear) * nd (Jul 1952), 192pp, 1/6.
411 Dubois, Theodora * Solution t-25 * nd (Jul 1952), 192pp, 1/6.
Zeigfreid, Karl * Chaos in Arcturus * nd (Oct 1953), 124pp, 1/6.
Futuristic Science Stories 13 * (Oct 1953), 128pp, 1/6.
Worlds of Fantasy 12 * (Feb 1954), 128pp, 1/6.
Futuristic Science Stories 15 * (Apr 1954), 128pp, 1/6.