Danny Samford owed no duty to Duff to anticipate Duff's unlawful and negligent conduct. Minugh v. Royal Crown Bottling Company, 267 S.W.2d 861 (Tex.Civ.App. — San Antonio 1954, writ ref'd); Strange v. Colvin, 429 S.W.2d 954 (Tex.Civ.App. — Austin 1968, n.w.h.); Smalley v. McMurray, 427 S.W.2d 118 (Tex.Civ.App. — Eastland 1968, n.w.h.). Under the facts in evidence, had Danny actually observed the Duff car as it was proceeding along Santa Fe, precautionary action on his part was not required. The Duff automobile was being driven at a reasonable and safe rate of speed, in a careful manner, and was under control of the driver. There was nothing about the manner in which Duff was operating his car that should have alerted Danny to any careless or negligent driving or should have warned him that Duff would ignore the red light.

In order to warrant a jury finding that the failure of plaintiff to keep such a lookout was a proximate cause of the injury, the injury must have been foreseeable by him in time to have avoided the accident. Salcido v. Bates, 436 S.W.2d 934 (Tex.Civ.App., Corpus Christi 1968, wr. ref. n.r.e.); Strange v. Colvin, 429 S.W.2d 954 (Tex.Civ.App., Austin 1968, n.w.h.); McCauley v. Lasher, 368 S.W.2d 49 (Tex.Civ.App., Texarkana 1963, wr. ref. n.r.e.). Proximate cause cannot be established by mere conjecture or guess, nor may it be presumed. It must be proved. Ussery v. Ewell Hodges, Inc., 417 S.W.2d 332 (Tex.Civ.App., Tyler 1967, wr. ref. n.r.e.); Leatherwood Drilling Co. v. TXL Oil Corp., 379 S.W.2d 693 (Tex.Civ.App., Dallas 1964, wr. ref. n.r.e.).

Appellant cites a number of cases holding that under the facts of those cases the plaintiff owed to the defendant no duty to anticipate defendant's unlawful and negligent conduct, and that the facts in evidence did not support findings of negligence of plaintiff and proximate cause. Minugh v. Royal Crown Bottling Co., Tex.Civ.App., 267 S.W.2d 861, wr. ref.; Kaufman v. Miller, Tex.Civ.App., 405 S.W.2d 820, rev. by Sup.Ct. on other grounds, 414 S.W.2d 164; Hooper v. Holt, Tex.Civ.App., 416 S.W.2d 916, n.w.h.; Strange v. Colvin, Tex.Civ.App., 429 S.W.2d 954, n.w.h.; Salcido v. Bates, Tex.Civ.App., 436 S.W.2d 934, wr. ref. n.r.e. We have examined these authorities, and have no quarrel with the holdings made on the facts and evidence of each such case.

In this case Salcido was not required to anticipate that Bates would fail to yield the right of way after passing the 'Yield' sign and as he approached the east edge of the main travelled portion of the highway. See Smalley v. McMurray, 427 S.W.2d 118 (Tex.Civ.App., Eastland 1968, n.w.h.); Strange v. Colvin, 429 S.W.2d 954 (Tex.Civ.App., Austin 1968, n.w.h.). Assuming that Salcido did not keep a proper lookout, as found by the jury, the evidence is factually insufficient to establish that such failure was a proximate cause of the collision or that he could have avoided it by a proper application of his brakes. The failure to keep a proper lookout can only be deemed a proximate cause where 'the keeping of it would have prevented the unfortunate occurrence.' Texas P. Ry. Co. v. Shoemaker, 98 Tex. 451, 84 S.W. 1049; Gulf, C. S.F. Ry. Co. v. Russell, 125 Tex. 443, 82 S.W.2d 948; Thompson v. Gray, 219 S.W.2d 831 (Tex.Civ.App., Galveston 1949, wr. ref. n.r.e.); Taylor v. Brooks, 392 S.W.2d 878 (Tex.Civ.App., Waco 1965, wr. ref. n.r.e.).