Deepseek is wrong about these two at least. Canary Islands and Faroe Islands both observe DST.
Since this is the SDMD I’m going to be pedantic here and point out that UTC and GMT are not the exact same thing. GMT is Greenwich Mean Time, i.e. mean solar time at the Greenwich meridian. It’s defined by nature, namely the apparent diurnal motion of the Sun across the Earth’s sky that results from the Earth’s rotation around its axis and its revolution around the Sun.
UTC (Universal Time Coordinated), on the other hand, is an artificial time standard. It’s a weighted average of the time measured by hundreds of atomic clocks around the world, so it is artificial. It was set such that on January 1, 1972, it was identical to GMT, but since the rotation of the Earth is not perfectly uniform, GMT and UTC have a potential to diverge from each other. To minimise these divergences, there’s a leap second inserted into or deducted from UTC when needed, to realign the two; the last time this occurred was in 2016. This is managed by a body with the very cool name “International Earth Rotation and Reference Systems Service”, which is essentially a network of observatories around the world that measure the Earth’s rotation to determine if a leap second is needed. They do it when the divergence between the two is about to exceed 0.9 seconds.
1972 was when the leap-second system started. In the 1960s UTC seconds were slightly longer than atomic-clock seconds, changing each year as needed to keep UTC close to mean solar time. Since 1972, UTC seconds have been honest seconds. I doubt they threw in another correction on 1 January 1972, trying to zero the error. (How long did it take in 1972 to determine the official “mean solar time”, finding UT0 and converting it to UT1, or whatever they need?)
I do not know the full answer to your question, but at that time the B.I.H. was publishing a monthly Circular D.