A qualitative examination of generalized valence bond pair correlation energies leads us to a quantitative relationship (interference effect) between basis set truncation errors in MP2 energies and basis set truncation errors in CCSD(T) energies. Thus, a knowledge of the MP2 complete basis set limit can be combined (for example) with CCSD(T)/[5s4p3d2f/4s3p2d] calculations to estimate the CCSD(T) limit to within +/-0.46 kcal/mol. Explicit MP2-R12 calculations are then compared to three extrapolation schemes employing cc-pVnZ correlation consistent basis sets in an attempt to find an inexpensive route to the required MP2 limit. The first employs the N-1 asymptotic convergence of pair natural orbital (PNO) expansions to extrapolate to the complete basis set (CBS2) Limit. The second employs (l + 1/2)(-3) extrapolations of more than one MP2/cc-pVnZ calculation to estimate this MP2 limit. The third method combines the PNO extrapolations with a linear and thus size-consistent (l + 1/2)(-3) extrapolation. This linear (l + 1/2)(-3) extrapolation of first CBS2/cc-pVDZ and CBS2/cc-pVTZ then CBS2/cc-pVDZ and CBS2/cc-pVQZ energies gives the absolute MP2-R12 limit to within +/-0.86 and +/-0.49 kcal/mol respectively for a test set of 12 small closed shell molecules, which represents a new level of accuracy for calculations fast enough to be routinely applied to molecules as large as naphthalene. Combining these MP2 limits with the interference corrected CCSD(T)/cc-pVDZ and CCSD(T)/cc-pVTZ energies respectively, gives the absolute CCSD(T) basis set limit to within +/-1.74 and +/-0.93 kcal/mol.