Yup, the Campbell tartan is based on the 42d Black Watch tartan, or also known as the Government sett.
You do know that the 'family' tartans were invented by the English in the 19th century, don't you? Before that, no Scottish family laid claim to any particular tartan, in fact the clansmen would wear one style for the kilt, another for their jacket, and even a third for the hose or bonnet. Early paintings of these guys look like a color riot!!