The Bridge has been described as a ‘secret Culture novel’, a mystical key to Banks’s literary universe. It blurred the boundaries between genres – and revealed his sense of fun and games • Reading group: The debt The Bridge owes to Alasdair Gray’s Lanark

Iain Banks was “two of our finest writers”, as Tom Chivers pointed out in a touching piece in the Telegraph. Approximately half of Banks’s novels were Earthbound, mainstream (or arguably literary) fiction. For the other half, he added the middle initial “M” to his name and wrote reach-for-the-skies science fiction: universe-traversing space opera generally set around the machine-mind utopia provided by the Culture fictional society.

Except, of course, as with most things related to Banks’s fiction (aside from his early covers), matters aren’t entirely black and white. The 2009 novel Transition, for instance, was published under the name Iain M Banks in the US, partly as Banks joked for “commercial reasons”, because by the time the book came out the Culture novels were outselling his Earthbound fiction in the US. Partly because it was an attempt to write “something like The Bridge” again – a complicated, multifaceted novel teasing out several complicated plot strands, loaded with symbolism and blurring the boundary between mainstream fiction and SF. A novel which is, in fact, a bridge between the two different elements of Banks’s career. A novel that also contains all kinds of references to the other universe Banks had already created in his mind.

Before discussing those connections, a quick point of order. Although the Iain M Banks books sold better in the US by the turn of the millennium, writing SF was not a commercial decision by Banks, as he explained during his final days:

Until the last few years or so, when the SF novels started to achieve something approaching parity in sales, the mainstream always out-sold the SF – on average, if my memory isn’t letting me down, by a ratio of about three or four to one. I think a lot of people have assumed that the SF was the trashy but high-selling stuff I had to churn out in order to keep a roof over my head while I wrote the important, serious, non-genre literary novels. Never been the case, and I can’t imagine that I’d have lied about this sort of thing, least of all as some sort of joke. The SF novels have always mattered deeply to me – the Culture series in particular – and while it might not be what people want to hear (academics especially), the mainstream subsidised the SF, not the other way round.

Science fiction was a passion and an obsession. Banks would have wanted to write it whatever happened – although as a canny commercial operator, he also took care not to alienate his core audience. Hence the M in his name. Hence, partly, The Bridge, a novel connecting the two different promontories of Banks’s fiction – a direct link between the Scottish themes of his earlier work and the universe he was about to unveil in his next release, Consider Phlebas.

The most obvious connections are abstract. The Bridge bends reality, breaks the rules of physics, invents technologies and plays around with impossible inventions. It also blurs the boundaries between life and death in ways that would have plenty of 1980s bookshelvers pushing it towards the genre zone. It’s worth noting that his source novel Alasdair Gray’s Lanark was originally marketed as SF in the US – where it tanked.

Other connections are more solid, but also stranger, and so abstruse that The Bridge has been labelled a “secret” Culture novel, by blogger Tom Bell. His post convinced me. I’d already spotted a few of the references – that knife-missile the Barbarian finds so irritating, for instance, also makes an appearance within the first 50 pages of Consider Phlebas, and keeps appearing in the rest of the Culture novels. But I also buy Bell’s arguments that the flying castle the Barbarian travels on in the later stages of the novel could be seen as a spaceship, that the “neuroscreening” helmets are similar to those in Culture novels and that the “Familiar” has striking similarities with Culture drones.

I’m sure there are plenty of other hidden links in the book; my own knowledge of Banks’s science fiction is too limited to spot them. But that isn’t really important. Indeed, I don’t think that knowing about the novels of the Culture series is likely to add much extra to your understanding of The Bridge. After all, it would be odd to release a book that only makes sense if you’ve read ones that haven’t yet been formally finished or published.

But it is tempting to view The Bridge as a kind of mystical key to the rest of his career – the vital piece in a multiyear plan. This was a writer with big ideas, not to mention plenty of earlier drafts of Culture novels that he hadn’t so far been able to publish. The Bridge was a connection to these future releases, and a neat way to air and test ideas that he had long been incubating.

Of course, that’s also a simplistic view. The Bridge clearly wasn’t only written to soften up literary fiction snobs or to introduce the concerns of the Culture worlds. Nor were the connections the book makes to Banks’s future SF only put in there to ease the minds of his readership. They are there because they are essential to the spirit, philosophy and plot of the book. Also – and this is why this subject is so alluring – I think Banks put most of this stuff in just for fun. He liked the ideas. He enjoyed the possibilities. He was playing games. He was living by a brilliant bit of advice he himself would give years later:

“In the end, writing about what you know – that hoary and potentially limiting, even stultifying piece of advice – might be best seen as applying to the type of story you’re thinking of writing rather than to the details of what happens within it and perhaps, with that in mind, a better precept might be to write about what you love, rather than what you have a degree of contempt for but will deign to lower yourself to, just to show the rest of us how it’s done.”

Seems like a sensible way to go about things.

• Reading group: How The Bridge crosses into Alasdair Gray’s Lanark