An ad campaign is probably trivialising what was clearly a campaign not to sell a product but to advocate for the traditional liturgy when the tide was perceived to be turning against it. The average person in the pew might believe the Church went from the old Mass to the new almost overnight. Seen in the context of the entire history of the Church some might argue it was little short of overnight. Nevertheless there were 5 years of official transition from the old liturgy to the new, with a new Ordo Missae in 1965, which was further reformed in 1967. Contiguous with this official universal reform was a melange of official, semi-official, unofficial and illicit experimentation and adaptation. Most of this was centred on and moulded by the local churches, almost invariably involving the introduction of the vernacular to the Mass to greater or lesser degrees.
In 1967 the Latin Mass Society had clearly taken fright. From February 1967 to February 1969 the LMS took out advertisements in The Clergy Review, placed at the beginning in the bod of the journal but soon they took out full-page ads on the inside of the front or back covers. The ads were every month except for April and September 1967, and January and November 1968. From March 1969 the LMS took out no more ads, one presumes either because they saw the die had been cast, or perhaps because they had run low on funds. I suspect the former.
The ads were interesting in the variety of their approach and I include some of them here as an historical curio. Swimming against the tide is a common experience for serious Catholics. This selection dates from 1968 but is representative of the general spread of the ads. I offer no commentary as others may be better placed to offer one.