Just how dark is His Dark Materials? The BBC, which has made a splendid adaptation (14-year-old Dafne Keen as Lyra is outstanding) of Philip Pullman’s bestselling trilogy, pondered long and hard about its tone, content and when to show the eight-parter. In the end it plumped for 8pm rather than 9pm, the traditional slot for its Sunday-night dramas. The earlier time gives more youngsters a chance to watch it “live”, even though the series’ lead producer, Jane Tranter, now an independent but who ran BBC Drama in the 2000s, argues that the TV version is “for adults which children can watch”.

Pullman has always refused to categorise his Dark Materials books. Yet there is child-snatching and medical experiments on those kids to remove their souls. Tranter counters that “children are going to be the least scared as they will not understand everything”. Probably not some of the physics and religion, but I reckon they’ll “get” being stolen by baddies.

This BBC One series, starting on 3 November and based mainly on Pullman’s first book, Northern Lights, will be followed this time next year by a second eight-parter, inspired by The Subtle Knife. The BBC has not, however, committed to a third (10-part) series of The Amber Spyglass. Good thing that His Dark Materials has the deep pockets of HBO and New Line Cinema, owned by Warner Bros, to support the Beeb.

Celebrating diversity: one of the images from Steve McQueen’s Year 3 project. Photograph: Tate

Look out for more than 600 billboards displaying seven- and eight-year-old schoolkids going up from Monday week in all of London’s boroughs. The huge posters are a fortnight-long prelude to Steve McQueen’s Year 3 photo project, which will be shown at Tate Britain from 12 November. Great advance publicity for the exhibition, which will show about 70,000 youngsters from the majority of the capital’s primary schools in class photographs that are being brought together in a giant installation in the Duveen Galleries.

The aim is to celebrate how diverse London schoolchildren are, and in a nice touch the images posted in each particular borough will feature kids from other boroughs. The billboard campaign, plus the considerable expense of taking the photos, is being borne in part by charities set up by Bloomberg and the late Cubby Broccoli, the James Bond film producer.

Invited back: the National Gallery 27. Photograph: Facebook

A few months ago, I wrote about the dismissal of 27 lecturers and educators, who had been working for many years at the National Gallery. They took their case to a tribunal earlier this year, receiving a judgment that they had been employed workers and not freelancers as the gallery claimed.

So a victory for the 27, which cost the National Gallery nearly half-a-million pounds in legal fees. Now, ironically, it’s inviting them back after realising that their less experienced replacements are not as good. And, despite knowing their backgrounds, the gallery is demanding three referees, proof of identity and assurances of no criminal record. How ridiculous.

A literary double for the Observer: both William Feaver, art critic of this paper from 1975 to 1998, and Laura Cumming, who has held the post for the past two decades, are on the shortlist of six for the Baillie Gifford prize, the top award for nonfiction. Feaver has been nominated for his biography of Lucian Freud and Cumming for her story of her mother’s mysterious kidnapping.