There was a moment, perhaps a decade ago, perhaps more, when the old world unravelled. It had actually been unravelling for some time, and I had been aware of it – for reasons we all knew.

I had been warned about the demise of the ‘mid-list author’ – those maintained as writers without huge success – because that was the business model the publishers used. This was a worry – I wasn’t sure, after ten years or so as a full-time writer, whether I had ever quite reached the heights of the mid-list.

I forget now when I realized that the world had changed, that consolidation in the book trade meant there was no longer any front door to knock on. There may have still been ways to get published, but they tended to be ‘round the back door’ – it meant my agent would need to have a quiet word to convince an editor that my new book would have a good chance in the latest roll of the dice.

I do have an agent, and he has been hugely supportive over the years. I just hope he gets something out of the relationship too.

So if 15 years ago I could earn up to half the money I needed to live on from writing books the old-fashioned way, by 10 years ago it was clear – given that I then had a young family to support – that I would need to do it differently.

I forget now what convinced me, and I have still been writing for the mainstream, like Broke (about the demise of the middle classes, with Fourth Estate) and How to be English (with Square Peg). But most of the time, the advances are meagre and I had to pull something out of the hat.

The hat remains pretty empty, I haven’t solved the problem – given that I just turned 60 and nobody in their right mind would employ me full time any more, even if I wanted that.

My wife Sarah is in the early stages of a career as a textiles designer. That is going brilliantly but the money is yet to roll in on the scale we would need. My own income fluctuates wildly, but I even it out by having my own company (I’m the only employee) which pays me a salary of around £32,000 plus business expenses like travel. Most of that is earned from writing in some form or another.

Thinking about it for this article, I realise three things have saved me from perjury or despair.

First, I’ve had a parallel and related career as a policy wonk in the thinktank world, which began as freelance staff for the green-tinged New Economics Foundation. This has usually meant writing reports, usually on local economics or co-production in public services (my two specialist subjects), sometimes speaking and sometimes meeting the most bizarre people. I have also written four books for thinktanks over recent years.

The high point was being asked to run an independent review on barriers to ‘choice’ for the Cabinet Office, which turned out – typical this – to be unremunerated. I must be the only independent reviewer to have funded myself partly on an advance (for Broke) and partly on tax credits.

I have since helped set up two thinktanks, one green and radical (New Weather) and one based in Westminster (Radix). Carrying out this salary exercise has shown me, with some discomfort, that I now earn about two thirds of my income from thinktanks.

The second revelation which has kept me going was meeting Richard Foreman, later of Endeavour Press, now of Sharpe Books, who has commissioned me to write a series of historical ebooks and first got me interested in the Enigma Code. This doesn’t exactly pay the bills, but my ebook biography of Alan Turing did very well (but cost only £1.99 so it didn’t make me rich either).

Third, and based on the success of Turing, it struck me that I could maybe commission myself to do something similar. I preferred not to call this self-publishing so I set up my own imprint (The Real Press) and published myself, my relatives, friends and a little way beyond. I find it very hard to say no, so the output has been more diverse than I meant it to be, but it does earn me a little money (I give my authors 60 per cent of royalties).

I’ve now forced myself to concentrate on very short books, about history and by people I know – after three decades working for myself, I prefer my business relationships to be as informal as possible.

None of these are recipes for success, and some of them – if I’m not careful – may be the opposite. I have very little idea, any more than anyone else, how best to market ebooks. The kindle market is shrinking and Amazon could tighten its stranglehold any time.

But it is fun, all of it. It keeps me rather worse than busy and I have no idea where the money is going to come from more than a few months ahead. Nobody, especially not publishers, likes the fact that I have written – and plan to continue to write – on a range of different subjects and in far too many sectors. All I can say is that they all look interconnected to me.

I am also highly dependent on my health holding up, and the best way of doing that – apart from eating well and not drinking – is to keep your fingers crossed.

Yes, I occasionally ask myself – like Tevye in The Fiddler on the Roof – whether it would “spoil some vast eternal plan/If I were a wealthy man…”

But I am also aware that I am also extremely lucky to live and work in the way I do.

I am, in that sense, at least, a wealthy man. Fingers crossed…