Josephine! - Restoring a Joe Waugh ladies tourer

He means roll it inside itself along its length - like the way you would roll a Swiss Roll.

Caustic soda will always work on an aluminium seatpost, given enough time. It might take a week, but it will dissolve the aluminium. Mix up some strong solution and top it up regularly, and wear some proper safety equipment. Perhaps mix a solution of the same strength and deposit a piece of test-aluminium in it to see how it's doing...

Be careful not to get it on the frame as it'll damage the paint.

I think I shall continue with this for the meantime. It's certainly always worked for me in the past too... I like the sound of doing a test bit too.