Anyone have any?

The desires attributes are low weight (less than or close to 1.25kg) and good battery life (more than or around 3 hours). The budget is about £200 but less is better and there are no objections to it not being "new" so second-hand/refurbished is okay.

3 hours for a netbook sounds incredulous, a Dell XPS 17 lasts longer than 3 hours with a core i5/Geforce GPU.

Have you considered an Asus EeePC? Apparently having very good battery life plus the Linux community has been adding a great deal of support.

I have a Acer 522. The good thing is the chip, a AMD C-50 with decent graphic capabilities.
So maybe there are other brands with similar specs.
Check this huge thread:
http://forum.notebookreview.com/gaming-software-graphics-cards/549760-amd-c-50-cpu-6250-gpu-performance-acer-522-review.html

I could play Arcanum off the battery for at least 4 hours on EEE PC 1000H, so a low range EEE might be what you need.
However they can be prone to charge leak due to cheap MB. If I leave the battery in the shut down unit for a week it dies to the point of not booting. If I take the battery out it remains almost fully charged.

Managed to find a 1000H (or 1000HE, depending on which of the title/description is accurate) for £110 on eBay. The difference between the weight on the eBay description and on reviews is huge (0.66kg vs. 1.45kg) so it's expected to be quite a bit heavier than desired/the one it is replacing.

Thanks for your suggestions grviper, aymerict and Kaustic :)