144 hour visa advice please

Hi there,

I am travelling to China and Japan in March, I think I qualify under the 144 hours twov scheme. Can you please confirm?

22 March - London to Hong Kong via Beijing (1.5 hr transfer time)
29 March - Hong Kong to Beijing (need to use the 144 here - staying for 3 nights)
1 April - Beijing to Japan
4 April Japan - London

Thank you

Hanifah