The water didn't appear to be rusty at all.
The botton bracket sealed units are sort-of suspended out of harms way, if you see what I mean, Simon, by the eccentric bottom bracket gubbins. It was pretty clear that, wherever this water has been over the past 8 weeks, it hasn't been in the bottom bracket area. It was only after I altered the frame's position after hoisting it towards the garage roof on a couple of lengths of rope that the water found its way out - through the bottom brackets.
The job I'm doing is replacing the rings and chains - long overdue - and I've removed the cranks as well. Both crank axels spin freely enough. I'm also going over the frame with Hammerite. It was a really crap paint job that Thorn did on this and, given how many Rohloffs Robin Thorn has supplied, I haven't got the stomach for yet another fight with him. Had it not been for the broken Rohloffs I definitely would have done. Paint has been flaking of around the BBs, and a few other places, for quite a while. I was considering getting the whole bike resprayed by Mercian, but the Hammerite (to my idosyncratic colour vision it's almost the same colour as the tandem's original paint) seens to be working fairly well so I'm applying further paint to some exposed metal. I will eventually get Mercian to do it, but I won't get any change from £300 when I do this, so I'm just botching it through at the moment. We are taking it to Holland for my nephew's wedding - which is 4 weeks today - so the bike has to look at its best.