Dominic Lawson: He'd never credit her, but Cameron is sounding more and more like Mrs Thatcher

So now the political battle line between Labour and Conservative has been drawn. Gordon Brown says we should all eat up, rather than waste the food on our plate. David Cameron, in clear opposition, tells us that we must take more responsibility for our spreading waistlines. Let the nation divide: puritans versus aesthetes.

Or perhaps not: David Cameron's speech, announcing that, "It's time to bring the ideas of 'right' and 'wrong' back into our national life", was about much more than dieting. Nevertheless it was pure bathos that he singled out "obesity" – of all things – as an example of "wrong" things to be avoided: there is a fashionable moral panic over obesity, which is in fact a perennial physical phenomenon of no moral significance whatsoever.

Still, it is certainly true that physical appearance is something over which the individual alone can exercise responsibility; to that extent, at least, one can see why the Conservative leader singled it out in his address on the need for more personal responsibility and less reliance on the state.

I wonder what that great preacher of personal responsibility, Margaret Thatcher, thought about Mr Cameron's speech, assuming she has been made aware of it. Mr Cameron, ever since he challenged for the leadership of the Conservative Party in 2005, has sought, rhetorically, to distance himself and the party from the lady.

"We believe that there is such a thing a thing as society," has been Cameron's continual refrain for the past three years, a long-running calculated criticism of Margaret Thatcher's most famous and controversial remark: "There is no such thing as society."

This startling phrase, understandably, is always separated from its context. It was uttered during the course of an interview in 1987 with Woman's Own magazine. What she said was this: "I think we have gone through a period in which too many children and people have been given to understand 'I have a problem, it is the Government's job to cope with it!'... and so they are casting their problems on society and who is society? There is no such thing! There are individual men and women and there are families and no government can do anything except through people and people look to themselves first. It is our duty to look after ourselves and also to help look after our neighbour and life is a reciprocal business...".

She went on to expound the virtues of family life, the voluntary sector and charity – exactly as David Cameron has done over recent months. His speech this week in Glasgow was still closer to the Thatcher blueprint.

He declared that: "We need to end the idea that the state gives you something for nothing. If you can work, you must work. We will insist on it, and believe me, we will stick to our guns when the going gets tough." And also that a Cameron government would ensure that: "Encouraging personal and social responsibility must be the cornerstone of everything ... the best regulation is self-regulation."

Not surprisingly, many on the left have denounced Cameron's speech, seeing its fulminations about obesity in particular as a barely-coded attack on the habits of the poor – especially as the Tory leader went on to argue that "poverty, or social exclusion" are too often described as if they were never anything to do with personal decisions, whereas in fact, "social problems are often the consequences of the choices that people make".

Cameron here is obviously drawing on the old distinction between the deserving and the undeserving poor, but unlike Margaret Thatcher he has the technique of being suggestive rather than dogmatic: so there are no phrases which are provocative enough to be held against him in perpetuity.

Indeed, a closer reading of Mrs Thatcher's "There is no such thing as society" interview reveals that she understood very well – every bit as well as David Cameron and his "modern compassionate Conservative Party" a generation later – that it could be extremely difficult for some young adults to "take responsibility" for their lives.

She told the interviewer from Woman's Own: "When you have got no one who is hungry or need be hungry, when you have got an education system that teaches everyone – not as good as we would wish – you are left with what? You are left with the problem of human nature and a child who has not had what we and many of your readers would regard as their birthright – a good home – it is those that we have to get out and help... For those children it is difficult to say 'You are responsible for your behaviour!' because they just have not had a chance and so I think that is one of the biggest problems and I think it is the greatest sin."

Some on the left have suggested that David Cameron is off his well-educated head to have delivered such a speech at the launch of the Conservative by-election campaign in solidly working class Glasgow East. It's obvious that the Conservatives will not win the by-election – the local threat to Labour comes from the Scottish National Party; but as an attempt to damage Labour by painting it as the party which is detached from "traditional morality" based on the family unit, Cameron's approach is characteristically shrewd.

Glasgow East is a constituency with a particularly high concentration of Catholic voters; and in any case, the "non -judgemental" moral liberalism which Cameron has suddenly taken to attacking is something to which only middle-class intellectuals feel strongly attached as a matter of principle – and such people are not thick on the ground in the council estates of Glasgow East.

A fascinating insight into this was provided by the composer/ conductor of the BBC Philharmonic, James MacMillan, a Scottish Catholic. He had been a chairman of a Labour Party branch, and described in a newspaper article his coal-face perspective of how, "the party was being pulled apart by conflicting cultural values. The new metropolitan elites, in London and Glasgow, would fiercely contest any connection between social breakdown and their highly valued liberal progressivism in matters of personal morality."

He went on to denounce the way in which, "the new middle-class Labour activist is quite happy to use the urban poor as voting fodder, paying lip-service to economic inequalities. What they are far more passionate about, though, is the promotion of recreational individualism and lifestyle liberalism. That is why Labour will lose the Glasgow East by-election."

You might have thought that David Cameron is an arch-example of the "new metropolitan elite" – that is certainly how he has been characterised by many of his critics in the Conservative Party when they have expressed their dissatisfaction with him in the past. Now, however, there is a by-election to fight, and David Cameron will use whatever weapons seem most appropriate. He will even steal from Margaret Thatcher's hymn-book - without, of course, anything as crass as an attribution.

d.lawson@independent.co.uk