In this paper, we use the distributions of luminosity (P) and radio size (D) to re-examine the consistency of the unified scheme of high-excitation radio galaxies and quasars in the recently updated 3CRR sample. Based on a standard cosmology, we derive theoretically and show from observed data, the luminosity limit above which the 3CRR objects are well-sampled. We find, on average, a quasar fraction $$\sim $$ 0.44 and galaxy-to-quasar size ratio $$\approx $$ 2. Assuming a relativistic outflow of jet materials, we find a mean angle to the line of sight in the range $$35^{\circ }\,\le \,\phi \,\le 44^{\circ }$$ for the quasars. On supposition of luminosity and orientation-dependent linear size evolution, expressed in a general functional form $$D_{(P,z,\phi )}\,\approx \,P^{\pm q}$$ (1+ $$z)^{-w}$$ sin $$\phi $$ , we show that above the flux detection threshold of the 3CRR sample, high-excitation galaxies and quasars undergo similar evolution with $$q = -\,0.5$$ ; $$w = -\,0.27$$ and luminosity independent evolution parameter $$x = 2.27$$ , when orientation effect is accounted for. The results are consistent with orientation-based unified scheme for radio galaxies and quasars.