I wonder if line converters were widely avaialble at that time. Note that in the quote above, Ardagh mentions TV sets in Alsace being “adapted” to receive German TV.
Of course, cross-border TV viewing also extended across the Iron Curtain. Here’s a passage about TV in a divided Berlin, again from Timothy Green’s 1972 book (click to enlarge):
The authorities in the Philippines have essentially revoked the broadcast licence of the largest commercial broadcaster over there, ABS-CBN. Most agree it’s because they were critical of President Duterte. Scary stuff, this could well be back to the times of a Marcos-style dictatorship.