The half-life of the 1405 keV level in 172Yb has been measured as T12/=0.42(6) ns by the generalised centroid-shift method. The E2 transition rate to the 2+01+ level is extremely low with B(E2)=2.6*10-3 Wu whereas the E0 transition matrix element is rho (E0)=0.014. The authors discuss the alternative interpretations of the level either as a mixed symmetry state with the appropriate choice of parameters within IBM-2 or as having a structure dominated by a quasineutron pair excitation (n7/2+(633)-n7/2+(633)) and (n1/2-(521)-n1/2-(521)).