From HongKong, visitors can apply for a visa through one of the embassy of Vietnam in HongKong below:
Embassy of Vietnam in HongKong, HongKong
Address: 15/F, Great Smart Tower, 230 Wan Chai Road, Wan Chai, HONG KONG, CHINA
Phone: (852) 2591 4517
Fax: (852) 2591 4524
Your Email: email@example.com
Apply for Vietnam visa on arrival for time saving then get visa stamped at the Vietnam airports.
From 1 July 2015 to 30 June 2016, all British passport holders travelling for tourism or business can enter Vietnam for up to a maximum of 15 days without a visa.
You must get a visa before you travel to Vietnam if you want to stay for longer than 15 days and/or if you wish to re-enter Vietnam within 30 days of your departure. If you plan to leave Vietnam and re-enter from another country make sure you get a multiple visit visa before travelling. Make sure you know before you travel the type of visa you need for the purpose and duration of your trip