The first rule for any aspiring British politician is: never slag off the NHS. The second, I’d wager, is to always sing the praises of unpaid volunteers.

The recent Civil Society Strategy, for example, included segments from numerous government ministers rhapsodising about the value that volunteers bring to society.

But while most people instinctively think that volunteering is almost always a good thing, the exact size and nature of volunteers’ contribution to the economy often remains quite vague. Yesterday, IPPR North published a short report that goes some way to addressing this.

Working with Tony Chapman at St Chad’s College, Durham University, we analysed data from over 3,500 third sector organisations in the North to shine some light on the contribution of volunteers to the Northern Powerhouse, and the extent to which different third sector organisations depend upon volunteers to keep going.

Some of the figures that we uncovered are truly impressive. There are 930,000 volunteers working with third sector organisations alone, and the sum of their activity, if paid, would be worth up to £800 million a year to the North’s economy. This doesn’t even tell us the whole picture – for example, our data doesn’t capture the contribution that unpaid workers make in the NHS, police and other public services.

But what is arguably most revealing is the fact that a huge 81% of third sector organisations in the North say that they “could not keep going” without the contribution of volunteers. More in-depth analysis of the role of volunteers confirms this – our analysis suggests that as many as three quarters of all organisations are ‘highly reliant’ upon volunteers.

This trend is at least partly explained by the fact that volunteers play such an important role within the very smallest organisations. We estimate that over two-thirds of all volunteering hours are through organisations with an annual income below £100,000. The very smallest organisations are the most likely to rely heavily upon volunteers, especially those who can give their time regularly and who can be trusted to work unsupervised and under their own initiative.

To illustrate the role of volunteers to small charities, consider the example of Reach Out to the Community. They are a fantastic small charity based in South Manchester, working to support people who are struggling with the most basic of needs: food and shelter. Until recently they were entirely staffed by a small team of dedicated volunteers, and are still heavily reliant upon them for their day-to-day activities.

Today, they have about 20 volunteers who give their time regularly – each of them is highly trained and adept at working with people who are often in highly vulnerable and stressful situations. Steph, who is a co-founder of the charity and, until recently, a volunteer herself, says that volunteers are “invaluable” to their day to day operation.

Organisations like Reach Out to the Community depend upon the sustained commitment of a small number of unpaid volunteers who are trusted to work regularly and independently. Because of this, their relationship with their volunteers is very different to that of others (particularly larger charities), who might offer volunteering opportunities primarily because of the benefits for the volunteers themselves, rather than the added value they bring.

This is not to suggest that third sector organisations shouldn't be offering large-scale and one-off volunteering opportunities. There is plenty of evidence that volunteering brings significant physical and mental health benefits – so it’s fantastic that large charities and groups like Comic Relief or ParkRun can mobilise people to give their time on a one-off or occasional basis.

But, as our report demonstrates, the needs of organisations that rely heavily upon volunteers for their day-to-day activities are often different from those of organisations with whom volunteers work mostly on a one-off or occasional basis.

This matters because, for years, the focus of policy has been on increasing the number of volunteers - think of David Cameron’s plan to boost the Big Society by giving fifteen million employees in the private and public sector the chance to take three days volunteering leave and, more recently, the pledge within the Civil Society Strategy to tackle the ‘obstacles’ in the way of people becoming more ‘active citizens’. This agenda has been taken up with enthusiasm by many within the sector, and this has been reflected in recent interest in micro-volunteering, and the opportunities afforded by digital to mobilise volunteers.

In itself, this focus is to be applauded. But it should be considered only part of a successful approach to volunteering. Put simply, increasing the numbers of new volunteers isn't necessarily what those small, volunteer-run organisations need most urgently.

Instead, they are more likely to value financial and in-kind support, including pro-bono advice, reduced rates for room hire, help with fundraising and back office support.

The importance of financial support to small charities should not be underestimated. Take YUMI (York Unifying Multicultural Initiative) as an example. YUMI is a volunteer-run intercultural network, based in York. At present, the organisation is solely run by volunteers, with a small group of currently six individuals giving their time on a regular basis.

Relying on volunteers alone can make it very hard to keep going as an organisation. Sara, who is the network's project co-ordinator (and who works largely on a voluntary basis), says that the nature of the group's work, which involves building trusting relationships with people who may be socially isolated, can take substantial amounts of time and commitment - which might be beyond what most people are prepared to commit to on an unpaid basis. Sara says that funding for a single paid position would allow the group to do much more dedicated outreach work and to build working relationships with other groups in the neighbourhood.

However, those who support civil society activity might sometimes struggle to justify funding this type of work. It doesn’t always get headlines. Instead, it is often about supporting work that is already in place, and providing stability and security to the very smallest grassroots organisations.

Given the considerable value of volunteers to their communities and to the North, funding this type of work is hugely important. Those who sing the praises of volunteering should take note.

Jack Hunter is a Research Fellow at IPPR North. He tweets @JackHunter_uk.

To donate to Reach Out to the Community, click here.

To learn about YUMI, click here.