<initial sketch>
Same single-seat constituencies as now. No need for boundary changes and for local reorganisation.
Same voting form, but used slightly differently. Not just a single “X” but the option to identify 2nd, 3rd and further preferences if voter’s 1st choice fails.
Manual count as now, but with some simple extra steps if there is no majority winner. Reallocation of votes for the least favoured candidate to voters’ next preference where one is specified.
All in all, a no brainer for immediate implementation, given
- the urgent need to change the current highly undemocratic and dangerous FPTP
- the time and effort it will take to implement any other plausible replacement for FPTP
- the total compatibility of PV with the two most likely alternatives (STV and AMS), and hence the suitability of PV as a first step towards either of them.