Shanghai to Hong Kong, can we use the 72 hour visa free transit

Hi,
We are from the UK flying to ShangHai. We will be staying there for less than 72 hours, so eligible for the 72 free transit upon arrival. We have flights booked to Hong Kong to show when we arrive. The information states that you need to have an entry permit for the next country. As a UK citizen we do not need it for Hong Kong. Are our UK passports and flight tickets from Shang-Hai to Hong Kong enough as we don't need to obtain an entry permit for Hong Kong?
Thank you