thank you for your comments. When I started looking at flights I assumed that this would be the case, but it appears that Air China cannot check through baggage for sone (or all?) routings through Shanghai. I spoke to Air China and they confirmed I would need to recheck the bags. The route from LGW to o PVG is quite new I think so perhaps in future a more standardised transit will be available as it is for some other airlines at PVG I believe. If it is possible by the time we leave then there should be no issue, but if not it sounds like we should still be ok to go through and recheck the bags.