The FRA is celebrating its 50th anniversary with a 50@50 competition, including all 16 (not 17 as it says on the website front page) races surviving from the 1970 calendar. I have noticed that, apart from the Manx Mountain Marathon, they are all in England, even though the FRA is a UK organisation. So presumably neither Ben Nevis nor Slieve Donard were in that first calendar, even though both were well-established races by 1970?
Another notable Scottish omission is Carnethy 5; it wasn't in the first calendar, but in 2020 it is the 50th Carnethy race, the first having been in 1971. Before 1981 the route was different, only including two of the current 5 hills. This race is significant for me, as the 1977 Carnethy junior race (only one hill) was my first fell/hill race.
One race that is included is Pendle, on the exact 50th anniversary of the founding of the FRA. This is also significant for me, having been my first fell race in England, in 1979.