I can't really claim to be a friend; my relationship with Iain was somewhere between one of the faceless hordes seen at SF conventions, and "guy I run into at the pub occasionally". However, I've known Iain and chatted with him at times since, I think, 1989 or 1990 or thereabouts. And, after getting over my initial awe of the giant of letters, subsequently discovered that he was a giant in other ways: big-hearted, kind, affable, humorous, angry at injustice.

There is probably no point in my writing an obituary. The newspapers are all over the generalities (for example, here), and if I had anything more intimate to add I wouldn't care to do so in public, out of respect for his family and friends.

However, I'd like to pause for a moment and reflect on my personal sense of loss. Iain's more conventional literary works were generally delightful, edgy and fully engaged with the world in which he set them: his palpable outrage at inequity and iniquity shone through the page. But in his science fiction he achieved something more: something, I think, that the genre rarely manages to do. He was intensely political, and he infused his science fiction with a conviction that a future was possible in which people could live better — he brought to the task an an angry, compassionate, humane voice that single-handedly drowned out the privileged nerd chorus of the technocrat/libertarian fringe and in doing so managed to write a far-future space operatic universe that sane human beings would actually want to live in (if only it existed).

Last night I was talking to a friend who, with Ken MacLeod, had been invited to visit Iain last week at home. Iain was apparently gravely ill even then, and had to retire after half an hour. Purely selfishly, I hoped he'd hang on longer — long enough for me to tell him I intend to dedicate my next (first) trilogy to him. (I can't hold a candle to his versatility as a writer, but it seems to me that we badly need an SF literature that offers hope for the future, and he has provided a compass for me to set my sails by.)

I've spent about 3 months away from home (Edinburgh) this year, so the last time I saw him was back in December or January, before his diagnosis. Purely by accident, I ran into him in the St James shopping centre (up the road from where I live). He was his usual affable, cheery self: and that is how I intend to remember him.

As Paul McAuley tweeted, a big bright bold boisterous light has gone out.