If you want Joanna's character without the Little Greene price tag, Dulux Cameo Silk 3 is your colour. It comes in at ΔE 0.8 from the original — and anything under 1 is imperceptible to the human eye, so on the wall you genuinely won't be able to tell them apart. LRV is 81.3, so it sits in that soft, light, gently warm bracket Joanna lives in.
Your backup is Dulux Dusted Moss 4 at ΔE 1.2 (LRV 81.5). Still a very close match — under 2.5 counts as very close — but Cameo Silk 3 just edges it. I'd only reach for Dusted Moss 4 if you're already using other shades from that Dulux strip and want to keep things tidy in one card.
Here's the thing worth flagging, mate: a colour match is not a finish match. Little Greene's Intelligent Matt Emulsion and their Absolute Matt have a particular depth and chalkiness that Dulux's standard trade or retail lines won't quite replicate, even with the colour spot-on. If it's the *look* of Little Greene you're after as much as the hue, that's where the difference shows — especially in raking light across a large wall. For most rooms it won't matter a jot, but in a hallway with strong side light you might notice the sheen behaves differently.
My practical advice: get a Dulux tester of Cameo Silk 3, paint two coats onto a bit of lining paper (not straight on the wall — old colour bleeds through and skews your read), and prop it up morning and evening. Joanna shifts a little with the light, and you'll want to see your match doing the same dance before you commit a whole tin.
If budget's the only reason you're switching, Cameo Silk 3 will do you proud.