Plane to Guangzhou > train to Hong Kong > train to Guangzhou > plane departing Guangzhou

Hi, I arrive by plane from Australia to Guangzhou and will be catching the high speed train to Hong Kong. 4 days later I will return from Hong Kong to Guangzhou by high speed train in the evening. Early the next morning I depart by plane to the United Kingdom. I will be using a British passport. I will have train tickets booked before arriving. Does this trip qualify for 24 hour transit without visa? Many thanks!