A letter-writer to the Times reminds us of how talks during the hung parliament of March 1974 between the then Tory leader (and incumbent PM), Ted Heath, and the then Liberal leader, Jeremy Thorpe, broke down over Heath's inability to promise electoral reform:
Robert Armstrong, then Heath's private secretary, kept a detailed and highly confidential account of the negotiations between Heath and the Liberal leader, Jeremy Thorpe, which was made public last year under the Freedom of Information Act.
The decisive meeting took place in No 10 on Sunday, March 3, 1974. Armstrong recorded that Thorpe asked for a firm undertaking on electoral reform, which he had raised in previous discussions. Thorpe reminded Heath that he had "drawn attention to the fact that his party had polled nearly six million votes in the election but had won only 14 seats, and asked what were the government's views on the subject of electoral reform. In his telephone conversation earlier in the day Mr Thorpe had adumbrated a proposal under which there would be a Speaker's conference, with the Conservative and Liberal parties committed in advance to what their spokesmen would recommend to it, and pledge to implement the result within six months. The Prime Minister explained to Mr Thorpe that he and his colleagues could not honourably undertake to deliver anything like this."
Thorpe replied that without it "there was no possibility of the Liberal Party agreeing to participating in the government at this stage, though that prospect might change if and when a measure of electoral reform were passed . . . [and] if there were to be any prospect of an arrangement between the two parties [short of coalition], it would be necessary for the Prime Minister and his colleagues to give more indication than the Prime Minister had so far given that they recognised the injustice of the present system and were in favour of changing it to a system of representation which was fairer to the minority groups".
Since no such indication was forthcoming, the discussions collapsed.
You can read the full memo here.
The Speaker's conference idea didn't take off in 1974. Tony Blair kicked the Jenkins commission report into the long grass. So will David Cameron really be able to fob Nick Clegg off with an "all-party inquiry" on electoral reform? I hope not, but in this election, as we've seen, anything can happen.