In the event, the Liberal Democrat surge petered out but it caused enormous disruption to the Tory campaign. Plans to attack Brown were abandoned and firepower was redirected towards Clegg. In addition, the debates have now institutionalised three party politics, making a Tory majority and strong governments much harder to achieve in future.
The debates were a lifeline for Brown that he was unable to take advantage of. They were a predictable and predicted breakthrough opportunity for the Liberal Democrats. Nick Clegg seized his opportunity with considerable skill. The Liberals have never broken through in a General Election in modern times because they could never match the financial muscle of the two main parties and they had little support in the written press. The massive audiences for the TV debates threatened to wipe out the advantage given to David Cameron by the support of key newspapers and by his Rolls Royce ground operation. They effectively gave the Liberal Democrats the same status they enjoy in by-elections where, unlike in national campaigns they are more than able to match the big parties; pound-for-pound, leaflet-for-leaflet, footsoldier-for-footsoldier. Fortunately for David Cameron the Liberal Democrats seemed as surprised by 'Cleggmania' as Conservative HQ. Although paralysed for 72 hours, Team Cameron did devise a plan to address the Liberal Democrats' debate bounce and Team Clegg never found a way of developing their advantage. Cameron improved by the second debate and won the third - largely by speaking more slowly, more directly and by addressing the bread and butter issues of tax, welfare and particularly immigration.
Debates will now be a feature of UK elections but consideration needs to be given to timetabling the debates over a longer period. Drawn out scheduling will make debates less dominant in the main campaign period and also give parties the opportunity to tackle any debate-induced surge by normal processes of examination.