In the last of three blogs on lobbying, Dominic Nutt asks how and why you should launch a public campaign to challenge government.

The SAS are a quality outfit. I’ve read all the books about the horrendous selection tests the hopefuls go through to become a part of the elite regiment and how they train to work behind enemy lines, undetected, creating a massively disproportionately effect, compared with the numbers of actual troopers on the ground.

Their skill and potency is, I guess, a function of the fact they get past all enemy defences into the heart of the enemy citadel where they can eyeball opponents and see in detail who they are, what they’re doing and where they’re going.

Last week Michael Clarke wrote about behind the scenes lobbyists, and why they are more effective.

There’s a lot to recommend this approach. Behind-the-scenes lobbyists are like the SAS of campaigners. They get up close to civil servants and ministers and engage them at close quarters.

It’s not a metaphor I want to stretch too far; I don’t advocate booby-trapping Sir Humphrey’s chair in the Department of Administrative Affairs, and in the end, backroom lobbying isn’t war, it’s about persuasion and working together – lobby group, politician and civil servant. At least in an ideal world.

But it’s not an ideal world and there are times when perhaps you sense that politicians and civil servants need a little extra shove. Or, perhaps, you are a charity or a lobby group that simply doesn’t have access to Whitehall in the first place. I want to talk about how to do it and when it’s better.

In which case you might want to start making a big fuss by creating a public noise, writing letters to MPs, waving placards about and kicking up a media storm.

This is easier said than done, of course. But in what circumstances might want to do it in the first place?

The first, I think is when you have no other option. Perhaps you’re a small organisation, under-resourced, inexperienced in the grey arts of lobbying, and perhaps way out of London where you can’t just pop in to Whitehall.

The first thing to do is look at your database of supporters, clients, friends and partners and discover if you have enough people to kick up some sand and get noticed.

This is the time when you will want to start writing to your local papers and place some news stories, roll out your case studies, make a few winning points and get some petitions going. Then your MP might take notice, and help you get in a national newspaper and win a meeting with a minister.

I’ve worked for big national and international charities which embarked on complex campaigns that no one understood and every political party wanted – initially at least – to run away from. The best examples I recall come from my time at the (in my view) brilliant campaigning organisation Christian Aid, where they used to take on the toughest international issues – not because they were easy and winnable, but because they were right.

I’m thinking of the campaigns to relieve international debt, to tackle climate change, and to recalibrate international trade rules so they favoured the poor. These are very, very hard sells.

Here’s the key thing. When a politician doesn’t want to engage – and try telling any elected official that she needs to campaign on preferential trade deals for poor countries – you’ve got to show them that voters care.

To do so, you have to get supporters out on the streets, to uncover the stories that make your case come alive in the media, to build the evidence base for your cases, and to unleash it in public – and do so, over and over and over again.

Politicians will get the message eventually and invite you in for talks.

I’ll give two examples. Back in 1996 (I think) the Prime Minister and Chancellor-in-waiting Tony Blair and Gordon Brown came to Christian Aid and were lobbied on the need for developing world debt relief.

To their credit both were enthused – and indeed eventually delivered massively on the policy. But in order to do so, they asked Christian Aid and others to deliver a constituency of support for the policy.

In other words, they wanted voters to campaign for it. And that is why Christian Aid and an alliance of other organisations, including CAFOD, got their supporters to send in postcards to the Chancellor (those supporters included Gordon Brown’s mother, who was a Christian Aid supporter) – and got thousands of supporters on the streets demanding the G8 forgive international debt.

It was a case of politicians and lobbyists working together to deliver global policy change.

And another, for me in recent months, working with the Department of Health on the Medical Innovation Bill. The DoH were onside, in theory at least, but sometimes allowed, shall we say, civil service inertia to get in the way of efficient and effective delivery of the Bill.

At such times, my role was to ensure a lot of media coverage, exposing the blockages, putting pressure on the civil servants’ political masters so that they would get a bit of an ear bashing from their boss. If someone was causing a problem, I would get the media and supporters to shout at them.

At the same time, we would also ensure our 40,000 supporters were emailing MPs and ministers supporting the Bill.

In meetings, we would all smile politely and draw gentle references to the media storm that either was happening - or might happen – in a given set of circumstances. And we would diplomatically suggest that the noise would increase if…

I do have a preference for public lobbying. For me, it has the clear virtue of transparency and allows opposition to make their case too. In a democracy, I think this is right. I don’t like the ‘under the radar’ approach.

In conclusion, there are times when backroom lobbying is the way to go. But just as the SAS can’t ultimately win a war – for that you need infantry; boots on the ground. In the end, to make a case, you need to win people and the media over.

Without public support, no policy can be effective. So there is always a case for public lobbying.

Dominic Nutt is a media consultant and formerly held senior communications roles at Christian Aid and Save the Children. He tweets from @DominicNutt