Well, I promised you an update after a week and.........IT WORKS!!! I can't believe it but it really does work! (In case you didn't catch the original post, here's the link...)
I mixed one spoonful of bicarbonate of soda (baking soda in USA) with 6 spoonfuls of cornflour (cornstarch in USA) in a little container which I keep in the bathroom. Each morning, when I've done my usual ablutions, I dampen my underarms then use my still damp fingers to pat the powder on till it feels dry. I do this leaning over the sink in case I spill any. It doesn't mark my clothes and it keeps me fresh and dry all day. It even worked when I did my exercise class - the rest of me got hot and sweaty (as it should if it's doing me any good) but there was no smell and no pit stains! (sorry if I'm being gross here) AMAZING!!!
And, of course, as well as needing no throwaway plastic container it is so cheap to buy. I reckon the amount I mixed will probably last a month or so, easily; and there's loads left in the packets I bought. Wow!
Sorry if I'm sounding a bit evangelical about all this but I can't believe how well it worked. To think of all the money I spent on useless chemical formulas in planet polluting packaging.... (Ooh, good bit of alliteration there.) Bet this is something the cosmetics companies want to keep veeerrrry quiet! ;-)