Why didn't Britain fight in Vietnam? (Short Animated Documentary)

I love these simple history animations....

Canada did, Australia did, New Zeland did, the Brits were tied up in Ireland

I'm not sure their involvement would have helped us or them. They were, and still are, trying to tamp down a history of colonialism that haunts them to this day. It likely would have been seen much more starkly by the vietnamese as a colonial land grab had Britain been involved.