From Pipes, Artisans and Trademarks, by José Manuel Lopes'

Regal is a former North American brand of the Regal Pipe Co. There are also models from Preben Holm and Butz-Choquin with this name.

Tom Colwell also mentions it as being connected with Linkman Co./Linkman Pipes

Ad and an example, courtesy Doug Valitchka