Thanks all- great info
That sounds reassuring.
The only possible issue I guess is that she is checking in on a UK passport without a Chinese visa.
From what you are saying though she should be able to show her pink card re-entry permit to the BA check in staff and hopefully they would know it qualifies her to get into PRC.
We will arrive with plenty of time to give an opportunity to check it out. Your KLM link may be helpful too.