[Neil Jones]

Not sure it's a myth, it was certainly in evidence last April for the DoE obit

tvhome.co.uk 

I wonder if the DofE idents that were used from the Saturday onward were knocked up at very short notice. Otherwise why not use them on the day itself?

They definitely weren’t knocked up in a weekend - someone found them hidden in the Sky Q software a few years before.

They weren't unique to Sky Q...
tvforum.uk 

(I never had Sky Q, just Sky+HD, and as I wrote there I could see the idents. They'd obviously been pushed to the Sky boxes (Q and HD+) presumably via the Anytime feature) at some point, though Sky had publicly scrapped Anytime in favour of on-demand/catch-up about a decade or so ago but since those boxes upgrade via satellite there's clearly still a download route available.

But yes, they weren't a "oh heavens the DoE's dead, let's slap something together" job. And I don't think they're part of the box software either - the hard drives in Sky boxes hold far more than stuff you've recorded yourself.