Here's a close-up of the battery holder and the corrosion. Luckily this is prior to the era of soldering cells onto the motherboard, with cataclysmic consequences when they leak, so the damage is limited to the casing, rather than the heart and soul of the Archimedes.
That's all from my new A410/1 for now - this set is just to whet your appetite fresh from the Wakefield Show, but there will be more detail on the insides and workings of it in the future!