London - Hong Kong - Shanghai - London

I'm a British citizen travelling from London (home) to Hong Kong direct, spending 2 days in HK, then flying direct to Shanghai for 2 days before flying direct back home to London.

This is one airline tickets using BA/Cathay Pacific/BA for the 3 flights - would this be covered by the 144hr Shanghai free transit, or, would i need to apply for a regular visa?

I'm unclear as all the examples I read are for outbound travel and not return to home country.