Back to the item in question though, surely you have to view the recording and their performance of it in the context of the time. It looks a bit cheesy and strait laced to our eyes and ears now, but at the time it was almost revolutionary to see chart artists playing their own instruments, and actually to hear any bass and drums in the mix. Check out the rest of the charts at that time.

From what I can remember of that time, the Shadows certainly did not appeal to your parents brought up on a diet of solo crooners, backed by unseen dance bands, which was another reason that teenagers would have taken to them. It was many years before my parents saw any merit in the Beatles recordings, but to modern ears their early stuff now sounds too accessible (easy listening) to be considered cool, notwithstanding the recent fashion for retro cool and tribute bands.