Ah, thanks for confirming, pretty certain that is what I ended up doing. If I recall, this did still have other issues, for instance handling scaling and origin

Ah, thanks for confirming, pretty certain that is what I ended up doing. If I recall, this did still have other issues, for instance handling scaling and origin was difficult, and also I think all the points had 10 decimal places unnecessarily. I needed to use web tools to get it into the right shape, although part of this may be that I was getting my head around the difficulties of how SVG works on the web, using viewBox rather than height/width attributes and so on.