Please advise when the 72hr period commences, is it from 00h01 following day of entry?

Chris, which airport will you arrive? In Beijing, it is counted from the moment you go through the procedure and get the stamp on your passport, according to the inspection team. In Guangzhou, Chengdu and other cities, it is counted from 00:00 next day.

Thank you for the reply Amanda. We are travelling through Beijing, we arrive 0600 and then leave 1200 three days later. On pure arrival and departure that would be 78 hrs. For a family of 5 the visa's would be £500 which is rather a lot for a few hours over. Taking into account about 1 hr to leave the plane and get through passport and arriving back at the airport 3 hrs before departure would mean only 74 hrs in Bejing, do you think we can manage on the 72hr permit?

Ah, I do think it's risky if you do not apply for the transit permit in advance and I'm afraid that the airline may not allow you to get on the plane. I advise you to dial Beijing Airport Immigration Inspection at 0086-10-56095400 and seek for their advice.

thanks I will do as you advise