One of the most trying things you have to do as a Labour adviser is persuading your boss to give up precious time, especially at the end of a long and stressful day, to attend a donor’s event for the party. Eyes roll. There are sighs and grumbles of “do I really have to do this? Can’t someone else go? I’ve got more important things to do.”

I can therefore sympathise with Jeremy Corbyn, who is reported to be shying away from meetings with the few major donors the Labour party has left. Truth is, these meetings are not always much fun. You can feel a bit of a show pony as you conduct a one-man/woman charm offensive, and quite often they can feel like a bad date.

But they have never been more important, because for the Labour party to function as an effective opposition to the Tories, it needs to be a well-resourced operation, and that means it needs money. We should not be bashful about this. Labour needs money like it’s never needed it before, because the Tories have cut off important funding streams for the party through the trade union bill and cuts to Short money, which opposition parties get from the state to help them do the job of holding the government to account. They have of course not touched the issue of placing a cap on donations, which is monstrously unfair.

What the Tories are doing is a brutal attack on British democracy – even Tory grandees such as Michael Forsyth think David Cameron has gone too far. But despite the united howls of outrage from Blairites to Corbynistas, sadly there is little that can be done. This is yet another vicious consequence of the Tories winning a majority at the general election.

Which is why the issue of trying to access other funding is all the more important for Labour. Of course there is always a justified squeamishness about money and politics. Party officials still shudder at the scandal of cash for peerages, which cast a stain, and are rightly mindful of sticking scrupulously to not just the letter of the law but indeed the spirit of the law. All politicians live under the shadow of the expenses scandal and the fact is that the public generally think that most of them are in it for the money.

I can imagine those fears and anxieties loom even larger in the minds of the team around Corbyn. Meeting rich people and asking for money is not exactly part of the brand that has been so successful among his party faithful. But like so much in political leadership, sometimes you just have to suck it up and do things you don’t like – whether it’s speak to the media, meet with donors or tour the exhibition stands at conference (sorry but it’s true – all leaders hate doing this).

You can fundraise in a way that is ethical and stays true to Labour party values, by sticking to the one very clear and simple principle that should run through every aspect of the relationship with a donor or potential donor: be crystal clear that there is nothing transactional about making a donation. There will never be any “reward” in terms of access to leadership, influence over policy, or party position, honour, parliamentary seat or peerage. That should apply to a wealthy individual, a company or a trade union. The message from Team Corbyn should be straight-talking honest politics. You should give money to Labour because you share the values and the vision of the party and you want to see the party win the next general election. You don’t get a policy veto or an office or a title or the hint of some other goody further down the line. And you should understand why you shouldn’t get any of these things.

In the past, there was occasionally a whiff of that type of tacit transaction, and in the end it didn’t prove very helpful to either side and wasted a lot of time massaging egos. There must now be clear firewalls between financial transactions and wider political conversations.

Most donors do understand this and it would be wrong to imply otherwise. Many want nothing at all – not even a nice seat at conference for the leader’s speech or an invite to a special event – and are content to give unconditionally.

It’s no secret that a lot of wealthy Labour donors are walking away as they don’t agree with the leadership. But there will be those who want to stay and new ones who want to get involved. Team Corbyn must reach out to them, invest the time and see it as an opportunity to cultivate important and fruitful relationships based on shared values, not individual rewards, which is surely at the heart of his politics. It’s not selling out to try to save the finances of the Labour party.