With a view to investigating the surface tensions of a (non-alkane+perfluoroalkane) mixture which, in a similar fashion to a typical (alkane+perfluoroalkane) mixture, displays large positive deviations from bulk ideality and large negative deviations from surface ideality, we have determined the orthobaric (gas+liquid) surface tension of tetrachloromethane at temperatures from 296 K to, and of (tetrachloromethane+tetradecafluoromethylcyclohexane) from T=303 K to T=315 K close to the upper critical solution temperature TUCS=302.23 K. The surface tensions of the mixture display both large negative deviations from surface ideality and a close-to-horizontal inflection like that first predicted by Widom for the tension of the noncritical interface of a mixture at a critical end point. Incidentally, but no less interestingly, the mixture comprises substances of almost equal vapour pressure -and hence is neither normal nor non-normal in the sense of the Widom definition whereby a normal mixture is one in which the more volatile component is of lower surface tension, or tautness. It is surprising, therefore, that the near-critical surface tension isotherms display an inflection of a nature more to be expected if the vapour pressures of the components were more different and tetradecafluoromethylcyclohexane was the more volatile.