Got it! But I would not have picked that up from reading http://www.pragma-ade.nl/general/manuals/xtables-mkiv.pdf, which was my guide for this particular exercise. It certainly says \placetable[here,split] but there is no mention of the \start...stop version of that.

Anyway, I now understand what I need to do, so thank you.

Julian

\startplacetable [location={here,split}]