I have a maximum of 275 minutes to shoot any one shot before my battery runs out. Removing the battery to recharge it means starting again with framing and exposure. So I am grateful to Nina Pope for my insulex tea pot which has a layer of air inbetween its inner and outer casing. The tea easily stays hot for 275 minutes. Now I just need some self control, to stop me eating all my biscuits in one go.