On its own AV would be unacceptable because of the danger that that in anything like present circumstances it might increase rather than reduce disproportionality and might do so in a way which is unfair to the Conservative Party.
The majority of MPs (80 to 85%) would continue to be elected on an individual constituency basis, with the remainder elected on a corrective top-up basis which would significantly reduce the disproportionality and the geographical divisiveness which are inherent in FPTP.