The next poor souls who have to fight a parliamentary by-election for the Labour or Conservative parties may as well start by changing their surname by deed poll to Kick-Me. For that is almost certainly what will happen. By-elections are not particularly representative affairs but they are not entirely inconsequential events either. They have become an odd political version of anger management sessions. Voters treat them as a chance to get something off their chest and are none too subtle with their language in so doing.

That was most obvious in the dismal fate of those who wore the red rosettes in Blaenau Gwent and in Bromley and Chislehurst. At the outset of the battle in South Wales, Labour had realistic hopes of retaking a Westminster seat that they had lost after a bitter dispute about all-women shortlists. As all of the main figures on the ballot paper were male and the party had apologised for the offence caused, there was reason to believe that normal Valleys political service would be resumed.

It was not, because Dai Davies, the independent who had taken up the colours of the late Peter Law MP, turned the contest into a de facto referendum on Tony Blair and new Labour. As the Prime Minister is about as popular in mainstream Welsh political circles as King Edward I, who invaded the country in the late 13th century, the frantic attempt of the Labour candidate to distance himself from Downing Street was doomed to failure. And in Bromley, his counterpart must have known that she did not have a prayer. Coming fourth to a spirited UKIP effort was close to inevitable. She will be grateful to have saved her deposit.

Yet, in a sense these by-elections revealed nothing about Mr Blair and the state of the Labour Party that was not obvious already. As the Prime Minister will not be taking the Labour Party into another general election, his standing with the electorate is not particularly relevant. To that extent, even if collectively the results were worse for Labour than the Tories, the inability of David Cameron to record any by-election “bounce” for himself or his party is the interesting element.

For as Jonathan Ross might have asked: “Dave, did you ever dream of winning the Bromley by-election by fewer than 700 votes?”. The answer to such an question has to be “no”. The Tories fought an awful campaign in this seat. They permitted a surly local party to impose its own candidate on the leadership, an individual who then proved to be something less than an asset. Mr Cameron paid one fleeting visit to the constituency and seemed almost embarrassed to be there. A casual elector who only studied the party literature pushed through his or her letter box could have been excused for assuming that Michael Howard had carried on as leader of the Opposition.

Future Tory by-election efforts will have to be more professional. Yet Mr Cameron should not escape all blame. There is anecdotal evidence of voters feeling that the Tory leader is but a younger and more lightweight version of Mr Blair, and that this is not what they are looking for. Mr Cameron is correct to think that in many, but not every, policy respect he needs to be closer to Blairite territory. This does not have to involve coming across to electors as an aspiring Rory Bremner as far as the Prime Minister himself is concerned. Bromley holds two messages for Mr Cameron: he must be the Tory message and he must have a message of substance to put before voters.