I was recently asked by a journalist on the radio: how does the government reaction to a possible fuel strike square with my Demos pamphlet, Stop The Union-Bashing? My reply was: I don’t see a contradiction in terms. There is a huge difference between millions of moderate union members, and some hardline union leaders, who Conservatives are bound to have disagreements with.

I have argued, however, that when we talk about trade unions, Conservatives need to change our language and our attitudes. Sometimes when we criticise unions, the effect is not just to demonise militancy, but every trade union member, including doctors, nurses and teachers. There is a world of difference between the policies of Len McCluskey, and the activities of the Unite trade union. In reality, Unite is a very capitalist organisation. On their website they advertise tax-minimising services through a business call “Tax Refund Co”, with the strapline: “Over £6.3 million already refunded to Unite members - see if you're due a refund.” They also advertise private health insurance deals through Eyecare Express, Macmillan Cancer Support, and Unite Family insurance, and there is even a “Unite Lottery”, a gambling game raising funds for the union.

It’s not just Unite. Many other unions offer identical services on their website. Unison, for example, also has private health schemes, and tax-avoiding services. And yet, both are formally affiliated with the Labour Party. This serves as a reminder that there are far more trade unionists with private health care, than who go on strike. The Daily Telegraph reported in 2001 that 3.5 million trade unionists—more than half the TUC membership—now have some form of private health cover. By contrast, the TUC estimate that just 2 million went on strike in 2011 over pensions reform. I joined Prospect, not because I agree with all of their political views, but because I know that if I got into a spot of bother, the union would be one of the first places to turn - especially if I needed legal advice or work support.

It is worth noting, however, that not only are unions very much capitalist, they are essential components of the Big Society. They are the largest voluntary groups in the UK. They are rooted in local communities, and are very much social entrepreneurs. TUC research shows that trade union officers are eight times more likely to engage in voluntary work than the average.

Disputes over pensions and wages will never make this relationship an easy sell. But the essence of my argument is that we cannot allow the Labour MP Denis MacShane to get away with tweeting that “Tories despise union folk”. It is simply not true. There are 6.5 million trade union members in the UK – more than the entire population of Scotland – and the majority of them are moderate, hard-working people. A Populus poll in 2009 showed that a third of Unite members intended to vote Conservative in the general election. The same was true of Unison. Of the 58 unions in the TUC, only 15 are Labour-affiliated, leaving 43 non-affiliated unions in Britain.

To be clear, I do not expect Bob Crow and other union barons to become Conservative voters. But given the extent of Conservative-minded thinking among union members, Conservatives should reach out to the membership, if not the leadership.

Contrary to popular mythology, Conservatives have not always been hostile to trade unions. Mrs Thatcher was herself an ardent trade unionist. Before New Statesman readers choke on their cornflakes, it is worth looking at the history. In 1951 one of the first political organisations she joined was the Conservative Trade Unionists (CTU). As Leader of the Opposition, she expanded CTU to more than 270 branches up and down the country, and even diverted Conservative Office funds to support the CTU with full-time staff. It is hard to imagine now, but in 1979, thousands of trade union members flew banners reading: “Trade Unions for a Conservative Victory” in Wembley Stadium before the general election. Her quarrel was with what she saw as militants, not the trade union movement as a whole. Most people associate the beginning of the union movement with the Labour Party, but it was actually a Conservative Prime Minister (the Earl of Derby) who set in train the laws to establish trade unions, in 1867.

Conservatives should not be afraid to praise the union movement or even encourage people to join up. In fact, I think we should go so far as to offer free membership to any Conservative-minded trade unionist. We need to show union members that we share similar values: not only for their capitalism, but for their communitarianism as well. A newly invigorated Conservative trade unionist movement should encourage Conservatives to campaign in trade unions again, standing for election as officials, just as they did under Margaret Thatcher. It’s no good Conservatives complaining that unions are dominated by the Left, if we don’t participate in the union movement.

Robert Halfon is MP for Harlow and the author of Stop the Union-Bashing, published by the think-tank Demos. He tweets at @halfon4harlowMP