Anthony Mayer was Chief Executive of the Greater London Authority (GLA) for eight years and was the Greater London Returning Officer who ran the Mayoral and London Assembly elections. He knows a thing or two about non-FPTP elections.
He has written a letter to The Times explaining why London brought in vote counting machines for the Mayoral elections.
A first-past-the-post election nearly always requires one count and one validation. An AV election nearly always requires successive rounds of counting, each needing validation.
If the political classes want results early on the Friday after the 22:00 Thursday closure of polling stations then with AV there is no choice but electronic counting. If the political classes are relaxed about results coming in over the weekend then manual counting is feasible, if more costly on account of more counting staff hours.
There are those who say that the cost of elections shouldn’t be a factor and while I have some sympathy with this view I don’t believe that AV is a step in the right direction, paying more for a worse system defies logic.