The Hague campaign had targeted the Redwood supporters' doubts in the final hours before the voting began. Mr Hague sent a personal message to selected Tory MPs with cuttings from the morning newspapers, condemning the pact as a "marriage made in hell".
Clarke supporters claimed the move would backfire, but it touched a raw nerve with Mr Redwood's Euro-sceptic supporters who had spent an agonising 24 hours since the alliance was announced deciding whether to vote for a Europhile, or desert Mr Redwood. In the end they refused to vote for Mr Clarke.
Michael Portillo yesterday joined Baroness Thatcher and Norman Lamont in the last push behind Mr Hague's campaign to stop Mr Clarke winning the leadership.
Both sides went all out for Mr Redwood's 38 votes from the second ballot, but the refusal of some former Redwood supporters to declare how they voted kept both sides guessing about the result until it was announced in Committee Room 10.
Mr Portillo, regarded by many as the "leader-in-waiting" until losing his seat at the general election, telephoned the Redwood supporters before they voted to urge them to back Mr Hague.
Lady Thatcher and the former chancellor, Mr Lamont, also joined in the last-minute telephone canvassing for the Hague camp. Lady Thatcher had lobbied MPs at Westminster on the eve-of-poll in the Commons tea room and the members' library. One of her admirers who voted for Mr Clarke said: "I had a message to ring her this morning. I did so, but she was out - and that was a great relief. I was not looking forward to a lecture."
The Clarke camp met early yesterday at their campaign headquarters in Abbey Orchard Street to plan the final hours, and to come up with an answer to Mr Hague's attack that the Clarke-Redwood alliance was "a deal not a solution", which proved their undoing. They decided to reassure MPs by comparing their pact to the successful right-left alliance between the Labour leader Tony Blair and his deputy, John Prescott.
Mr Clarke went on BBC Radio 4's Today programme yesterday to claim that an alliance of opposites had helped Labour regain power, and the line was soon being pushed by Mr Clarke's supporters in the members' tea room.
Mr Redwood's supporters were deeply unhappy about his pact with Mr Clarke. Iain Duncan-Smith, one of Mr Redwood's closest allies, was among those torn over which way to vote, according to his friends.
The Clarke camp used the results of the ballot of Tory constituency chairmen to try to emphasise that Mr Clarke had wider appeal in the country than Mr Hague. Mr Clarke won that ballot by 277 votes to 206.
As the Hague and Clarke campaign managers ticked off lists of promised votes, it was said that five had slipped away to Mr Hague because of "the bad chemistry" of the Clarke-Redwood marriage, while two second-ballot Hague voters went over to Clarke.
When the result was announced another thing became clear - many MPs had lied about their intentions.